|
|
Tantalum Capacitors - Polymer 16V 10uF 20% 1210 ES R=100mOhm Black Resi
- TCJB106M016R0100E
- KYOCERA AVX
-
1:
$1.76
-
2,887In Stock
|
Mouser Part No
581-TCJB106M16R0100E
|
KYOCERA AVX
|
Tantalum Capacitors - Polymer 16V 10uF 20% 1210 ES R=100mOhm Black Resi
|
|
2,887In Stock
|
|
|
$1.76
|
|
|
$1.22
|
|
|
$0.899
|
|
|
$0.752
|
|
|
$0.702
|
|
|
$0.638
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
10 uF
|
16 VDC
|
SMD/SMT
|
20 %
|
1210
|
100 mOhms
|
16 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
TCJ J-CAP
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 10V 33uF 1311 20% ESR=80mOhms
- T525T336M010ATE080
- KEMET
-
1:
$1.76
-
2,900In Stock
|
Mouser Part No
80-T525T336M10ATE80
|
KEMET
|
Tantalum Capacitors - Polymer 10V 33uF 1311 20% ESR=80mOhms
|
|
2,900In Stock
|
|
|
$1.76
|
|
|
$1.17
|
|
|
$0.934
|
|
|
$0.863
|
|
|
$0.704
|
|
|
$0.657
|
|
Min.: 1
Mult.: 1
:
3,000
|
|
|
33 uF
|
10 VDC
|
SMD/SMT
|
20 %
|
1411
|
80 mOhms
|
33 uA
|
1.1 mm
|
- 55 C
|
+ 125 C
|
3528
|
T Case
|
T525
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 6.3V 47uF 1311 20% ESR=70mOhms AEC-Q200
- T591B476M006ATE070
- KEMET
-
1:
$1.17
-
4,090In Stock
|
Mouser Part No
80-T591B476M006E70
|
KEMET
|
Tantalum Capacitors - Polymer 6.3V 47uF 1311 20% ESR=70mOhms AEC-Q200
|
|
4,090In Stock
|
|
|
$1.17
|
|
|
$0.601
|
|
|
$0.55
|
|
|
$0.464
|
|
|
$0.437
|
|
|
$0.414
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
47 uF
|
6.3 VDC
|
SMD/SMT
|
20 %
|
1311
|
70 mOhms
|
29.6 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T591
|
AEC-Q200
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 2.5V 100uF 1311 20% ESR=70mOhms AEC-Q200
- T598B107M2R5ATE070
- KEMET
-
1:
$1.22
-
3,184In Stock
|
Mouser Part No
80-T598B107M2R5ATE70
|
KEMET
|
Tantalum Capacitors - Polymer 2.5V 100uF 1311 20% ESR=70mOhms AEC-Q200
|
|
3,184In Stock
|
|
|
$1.22
|
|
|
$0.765
|
|
|
$0.704
|
|
|
$0.60
|
|
|
$0.568
|
|
|
$0.568
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
100 uF
|
2.5 VDC
|
SMD/SMT
|
20 %
|
1311
|
70 mOhms
|
25 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T598
|
AEC-Q200
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 50V 2.2uF 3528 20% ESR=150mOhms AECQ200
- T598B225M050ATE150
- KEMET
-
1:
$1.37
-
3,822In Stock
|
Mouser Part No
80-T598B225M50ATE150
|
KEMET
|
Tantalum Capacitors - Polymer 50V 2.2uF 3528 20% ESR=150mOhms AECQ200
|
|
3,822In Stock
|
|
|
$1.37
|
|
|
$0.712
|
|
|
$0.654
|
|
|
$0.556
|
|
|
$0.526
|
|
|
$0.50
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
2.2 uF
|
50 VDC
|
SMD/SMT
|
20 %
|
1311
|
150 mOhms
|
11 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T598
|
AEC-Q200
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 35V 33uF 3528 20% ESR=150mOhms AECQ200
- T598B335M035ATE150
- KEMET
-
1:
$1.21
-
4,709In Stock
|
Mouser Part No
80-T598B335M35ATE150
|
KEMET
|
Tantalum Capacitors - Polymer 35V 33uF 3528 20% ESR=150mOhms AECQ200
|
|
4,709In Stock
|
|
|
$1.21
|
|
|
$0.615
|
|
|
$0.563
|
|
|
$0.476
|
|
|
$0.461
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
3.3 uF
|
35 VDC
|
SMD/SMT
|
20 %
|
1311
|
150 mOhms
|
11.6 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T598
|
AEC-Q200
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 10V 22uF 20% 1210 ES R=70mOhm Black Resin
- TCJB226M010R0070E
- KYOCERA AVX
-
1:
$1.36
-
3,380In Stock
|
Mouser Part No
581-TCJB226M010R070E
|
KYOCERA AVX
|
Tantalum Capacitors - Polymer 10V 22uF 20% 1210 ES R=70mOhm Black Resin
|
|
3,380In Stock
|
|
|
$1.36
|
|
|
$0.948
|
|
|
$0.699
|
|
|
$0.584
|
|
|
$0.502
|
|
|
View
|
|
|
$0.547
|
|
|
$0.475
|
|
|
$0.447
|
|
|
$0.444
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
22 uF
|
10 VDC
|
SMD/SMT
|
20 %
|
1210
|
70 mOhms
|
22 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
TCJ J-CAP
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 16V 10uF 20% 1210 ES R=100mOhm
- TCJT106M016R0100
- KYOCERA AVX
-
1:
$2.48
-
2,771In Stock
|
Mouser Part No
581-TCJT106M016R0100
|
KYOCERA AVX
|
Tantalum Capacitors - Polymer 16V 10uF 20% 1210 ES R=100mOhm
|
|
2,771In Stock
|
|
|
$2.48
|
|
|
$1.76
|
|
|
$1.51
|
|
|
$1.33
|
|
|
View
|
|
|
$0.975
|
|
|
$1.17
|
|
|
$1.06
|
|
|
$0.975
|
|
Min.: 1
Mult.: 1
Max.: 10,000
:
2,500
|
|
|
10 uF
|
16 VDC
|
SMD/SMT
|
20 %
|
1210
|
100 mOhms
|
16 uA
|
1.2 mm
|
- 55 C
|
+ 125 C
|
3528
|
T Case
|
TCJ J-CAP
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 35V 15uF 20% 3528-21 -55 /+125C ESR=200mOhms
- T521B156M035ATE200
- KEMET
-
1:
$1.26
-
560In Stock
-
2,000Expected 2027/04/29
-
New Product
|
Mouser Part No
80-T521B156M35ATE200
New Product
|
KEMET
|
Tantalum Capacitors - Polymer 35V 15uF 20% 3528-21 -55 /+125C ESR=200mOhms
|
|
560In Stock
2,000Expected 2027/04/29
|
|
|
$1.26
|
|
|
$0.848
|
|
|
$0.618
|
|
|
$0.512
|
|
|
$0.476
|
|
|
$0.38
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
15 uF
|
35 VDC
|
SMD/SMT
|
20 %
|
1411
|
200 mOhms
|
52.5 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T521
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 10V 47uF 20% SnPb 5% Pb min ESR=70mOhms AEC-Q200
- T598B476M010AHS070
- KEMET
-
1:
$4.93
-
1,444In Stock
|
Mouser Part No
80-T598B476M010AHS70
|
KEMET
|
Tantalum Capacitors - Polymer 10V 47uF 20% SnPb 5% Pb min ESR=70mOhms AEC-Q200
|
|
1,444In Stock
|
|
|
$4.93
|
|
|
$3.56
|
|
|
$3.01
|
|
|
$2.84
|
|
|
View
|
|
|
$2.33
|
|
|
$2.55
|
|
|
$2.54
|
|
|
$2.33
|
|
Min.: 1
Mult.: 1
:
2,000
|
No
|
|
47 uF
|
10 VDC
|
SMD/SMT
|
20 %
|
1411
|
70 mOhms
|
47 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T598 SnPb
|
AEC-Q200
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 10V 33uF 1311 20% ESR=80mOhms
- T540B336M010AH6710
- KEMET
-
1:
$18.69
-
300In Stock
|
Mouser Part No
80-T540B336M10AH6710
|
KEMET
|
Tantalum Capacitors - Polymer 10V 33uF 1311 20% ESR=80mOhms
|
|
300In Stock
|
|
|
$18.69
|
|
|
$14.27
|
|
|
$12.72
|
|
|
$11.46
|
|
Min.: 1
Mult.: 1
:
100
|
No
|
|
33 uF
|
10 VDC
|
SMD/SMT
|
20 %
|
1411
|
80 mOhms
|
33 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T540 HRA
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 6V 100uF 20% SnPb 5% Pb min ESR=45mOhms AEC-Q200
- T598B107M006AHS045
- KEMET
-
1:
$5.22
-
1,516In Stock
|
Mouser Part No
80-T598B107M006AHS45
|
KEMET
|
Tantalum Capacitors - Polymer 6V 100uF 20% SnPb 5% Pb min ESR=45mOhms AEC-Q200
|
|
1,516In Stock
|
|
|
$5.22
|
|
|
$3.78
|
|
|
$3.20
|
|
|
$3.04
|
|
|
View
|
|
|
$2.62
|
|
|
$2.73
|
|
|
$2.71
|
|
|
$2.62
|
|
Min.: 1
Mult.: 1
:
2,000
|
No
|
|
100 uF
|
6 VDC
|
SMD/SMT
|
20 %
|
1411
|
45 mOhms
|
60 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T598 SnPb
|
AEC-Q200
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 6.3V 68uF 1311 20% ESR=70mOhms AEC-Q200
- T591B686M006ATE070
- KEMET
-
1:
$1.33
-
190In Stock
|
Mouser Part No
80-T591B686M6ATE70
|
KEMET
|
Tantalum Capacitors - Polymer 6.3V 68uF 1311 20% ESR=70mOhms AEC-Q200
|
|
190In Stock
|
|
|
$1.33
|
|
|
$0.733
|
|
|
$0.656
|
|
|
$0.472
|
|
|
$0.445
|
|
|
$0.422
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
68 uF
|
6.3 VDC
|
SMD/SMT
|
20 %
|
2917
|
70 mOhms
|
42.8 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T591
|
AEC-Q200
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 3V 150uF 1311 20% ESR=80mOhms
- T525B157M003ATE080
- KEMET
-
1:
$1.35
-
1,145In Stock
|
Mouser Part No
80-T525B157M003
|
KEMET
|
Tantalum Capacitors - Polymer 3V 150uF 1311 20% ESR=80mOhms
|
|
1,145In Stock
|
|
|
$1.35
|
|
|
$0.918
|
|
|
$0.668
|
|
|
$0.554
|
|
|
$0.516
|
|
|
$0.409
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
150 uF
|
3 VDC
|
SMD/SMT
|
20 %
|
1411
|
80 mOhms
|
45 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T525
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 6.3V 33uF 1311 20% ESR=80mOhms
- T525B336M006ATE080
- KEMET
-
1:
$1.22
-
1,949In Stock
|
Mouser Part No
80-T525B336M6ATE80
|
KEMET
|
Tantalum Capacitors - Polymer 6.3V 33uF 1311 20% ESR=80mOhms
|
|
1,949In Stock
|
|
|
$1.22
|
|
|
$0.621
|
|
|
$0.569
|
|
|
$0.48
|
|
|
$0.454
|
|
|
$0.429
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
33 uF
|
6.3 VDC
|
SMD/SMT
|
20 %
|
1411
|
80 mOhms
|
20.8 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T525
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 50V 2.2uF 3528 20% ESR=150mOhms AEC-Q200
- T591B225M050ATE150
- KEMET
-
1:
$1.42
-
2,020In Stock
|
Mouser Part No
80-T591B225M50ATE150
|
KEMET
|
Tantalum Capacitors - Polymer 50V 2.2uF 3528 20% ESR=150mOhms AEC-Q200
|
|
2,020In Stock
|
|
|
$1.42
|
|
|
$0.737
|
|
|
$0.678
|
|
|
$0.577
|
|
|
$0.547
|
|
|
$0.516
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
2.2 uF
|
50 VDC
|
SMD/SMT
|
20 %
|
1311
|
150 mOhms
|
11 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T591
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 6.3V 22uF 20% 1210 E SR=70mOhm Black Resi
- TCJB226M006R0070E
- KYOCERA AVX
-
1:
$1.27
-
1,989In Stock
|
Mouser Part No
581-TCJB226M006R070E
|
KYOCERA AVX
|
Tantalum Capacitors - Polymer 6.3V 22uF 20% 1210 E SR=70mOhm Black Resi
|
|
1,989In Stock
|
|
|
$1.27
|
|
|
$0.649
|
|
|
$0.595
|
|
|
$0.504
|
|
|
$0.495
|
|
|
$0.451
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
22 uF
|
6.3 VDC
|
SMD/SMT
|
20 %
|
1210
|
70 mOhms
|
13.9 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
TCJ J-CAP
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 35V 4.7uF 1311 20% ESR=200mOhm AEC-Q200
- T591B475M035ATE200
- KEMET
-
1:
$1.33
-
2,732In Stock
|
Mouser Part No
80-T591B475M35ATE200
|
KEMET
|
Tantalum Capacitors - Polymer 35V 4.7uF 1311 20% ESR=200mOhm AEC-Q200
|
|
2,732In Stock
|
|
|
$1.33
|
|
|
$0.683
|
|
|
$0.626
|
|
|
$0.531
|
|
|
$0.501
|
|
|
$0.476
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
4.7 uF
|
35 VDC
|
SMD/SMT
|
20 %
|
1311
|
200 mOhms
|
16.5 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T591
|
AEC-Q200
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 35V 2.2uF 3528 20% ESR=150mOhms AECQ200
- T598B225M035ATE150
- KEMET
-
1:
$1.12
-
3,502In Stock
|
Mouser Part No
80-T598B225M35ATE150
|
KEMET
|
Tantalum Capacitors - Polymer 35V 2.2uF 3528 20% ESR=150mOhms AECQ200
|
|
3,502In Stock
|
|
|
$1.12
|
|
|
$0.563
|
|
|
$0.515
|
|
|
$0.433
|
|
|
$0.408
|
|
|
$0.391
|
|
Min.: 1
Mult.: 1
Max.: 4,000
:
2,000
|
|
|
2.2 uF
|
35 VDC
|
SMD/SMT
|
20 %
|
1311
|
150 mOhms
|
7.7 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T598
|
AEC-Q200
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 2.5V 100uF 20% 1210 ESR=70mOhm
- TCJB107M002R0070
- KYOCERA AVX
-
1:
$1.34
-
2,118In Stock
|
Mouser Part No
581-TCJB107M2R70
|
KYOCERA AVX
|
Tantalum Capacitors - Polymer 2.5V 100uF 20% 1210 ESR=70mOhm
|
|
2,118In Stock
|
|
|
$1.34
|
|
|
$0.933
|
|
|
$0.687
|
|
|
$0.576
|
|
|
$0.494
|
|
|
View
|
|
|
$0.537
|
|
|
$0.466
|
|
|
$0.44
|
|
|
$0.436
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
100 uF
|
2.5 VDC
|
SMD/SMT
|
20 %
|
1210
|
70 mOhms
|
25 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
TCJ J-CAP
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 6.3V 33uF 20% 1210 E SR=200mOhm
- TCJB336M006R0200
- KYOCERA AVX
-
1:
$1.40
-
3,222In Stock
|
Mouser Part No
581-TCJB336M6R200
|
KYOCERA AVX
|
Tantalum Capacitors - Polymer 6.3V 33uF 20% 1210 E SR=200mOhm
|
|
3,222In Stock
|
|
|
$1.40
|
|
|
$0.956
|
|
|
$0.697
|
|
|
$0.577
|
|
|
$0.491
|
|
|
View
|
|
|
$0.536
|
|
|
$0.462
|
|
|
$0.429
|
|
|
$0.416
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
33 uF
|
6.3 VDC
|
SMD/SMT
|
20 %
|
1210
|
200 mOhms
|
20.8 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
TCJ J-CAP
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 8V 33uF 1311 20% ESR=80mOhms
- T525T336M008ATE080
- KEMET
-
1:
$1.49
-
2,780In Stock
|
Mouser Part No
80-T525T336M8ATE80
|
KEMET
|
Tantalum Capacitors - Polymer 8V 33uF 1311 20% ESR=80mOhms
|
|
2,780In Stock
|
|
|
$1.49
|
|
|
$0.777
|
|
|
$0.714
|
|
|
$0.609
|
|
|
$0.577
|
|
|
$0.536
|
|
Min.: 1
Mult.: 1
:
3,000
|
|
|
33 uF
|
8 VDC
|
SMD/SMT
|
20 %
|
1411
|
80 mOhms
|
26.4 uA
|
1.1 mm
|
- 55 C
|
+ 125 C
|
3528
|
T Case
|
T525
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 16V 10uF 20% 1210 ES R=100mOhm
- TCJB106M016R0100
- KYOCERA AVX
-
1:
$1.12
-
3,222In Stock
|
Mouser Part No
581-TCJB106M016R0100
|
KYOCERA AVX
|
Tantalum Capacitors - Polymer 16V 10uF 20% 1210 ES R=100mOhm
|
|
3,222In Stock
|
|
|
$1.12
|
|
|
$0.598
|
|
|
$0.548
|
|
|
$0.462
|
|
|
$0.436
|
|
|
$0.418
|
|
Min.: 1
Mult.: 1
Max.: 8,000
:
2,000
|
|
|
10 uF
|
16 VDC
|
SMD/SMT
|
20 %
|
1210
|
100 mOhms
|
16 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
TCJ J-CAP
|
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 2.5V 100uF 1311 20% ESR=55mOhms AEC-Q200
- T598B107M2R5ATE055
- KEMET
-
1:
$1.49
-
2,710In Stock
|
Mouser Part No
80-T598B107M2R5ATE55
|
KEMET
|
Tantalum Capacitors - Polymer 2.5V 100uF 1311 20% ESR=55mOhms AEC-Q200
|
|
2,710In Stock
|
|
|
$1.49
|
|
|
$0.779
|
|
|
$0.683
|
|
|
$0.612
|
|
|
$0.579
|
|
|
$0.551
|
|
Min.: 1
Mult.: 1
:
2,000
|
|
|
100 uF
|
2.5 VDC
|
SMD/SMT
|
20 %
|
1311
|
55 mOhms
|
25 uA
|
1.9 mm
|
- 55 C
|
+ 125 C
|
3528
|
B Case
|
T598
|
AEC-Q200
|
Reel, Cut Tape, MouseReel
|
|
|
|
Tantalum Capacitors - Polymer 16V 10uF 20% 1210 ES R=200mOhm
- TCJT106M016R0200
- KYOCERA AVX
-
1:
$2.29
-
1,113In Stock
|
Mouser Part No
581-TCJT106M016R0200
|
KYOCERA AVX
|
Tantalum Capacitors - Polymer 16V 10uF 20% 1210 ES R=200mOhm
|
|
1,113In Stock
|
|
|
$2.29
|
|
|
$1.56
|
|
|
$1.27
|
|
|
$1.17
|
|
|
View
|
|
|
$0.928
|
|
|
$1.03
|
|
|
$0.979
|
|
|
$0.928
|
|
Min.: 1
Mult.: 1
:
2,500
|
|
|
10 uF
|
16 VDC
|
SMD/SMT
|
20 %
|
1210
|
200 mOhms
|
16 uA
|
1.2 mm
|
- 55 C
|
+ 125 C
|
3528
|
T Case
|
TCJ J-CAP
|
|
Reel, Cut Tape, MouseReel
|
|
South Africa