What do the letters in SR721SW mean?

S is silver oxide in the IEC system (S happens to match silver), and R means round. Same size with an LR prefix is alkaline — related size family, not the same battery. Full guide: CR vs LR vs SR.

What is SR721SW also called?

SR721SW pack labels and aliases on this site include 362, 361, SR721W, V362, V361, D362, D361, SR58. These are names for the same battery entity — not chemistry substitutes.

Battery

SR721SW

1.55V silver oxide button cell

SR721SW is a silver-oxide watch cell (about 7.9 × 2.1 mm). Jeweller packs often say 362 (361 is the related high/low-drain twin label). Not a lithium CR coin. See watch battery size codes.

Chemistry: silver_oxide
Voltage: 1.55 V
Diameter: 7.9 mm
Thickness: 2.1 mm
Used by: 0 devices

Common uses: Watches

Common questions

What is a SR721SW battery?: SR721SW is a silver-oxide watch cell (about 7.9 × 2.1 mm). Jeweller packs often say 362 (361 is the related high/low-drain twin label). Not a lithium CR coin. See watch battery size codes.
What do the letters in SR721SW mean?: S is silver oxide in the IEC system (S happens to match silver), and R means round. Same size with an LR prefix is alkaline — related size family, not the same battery. Full guide: CR vs LR vs SR.
What is SR721SW also called?: SR721SW pack labels and aliases on this site include 362, 361, SR721W, V362, V361, D362, D361, SR58. These are names for the same battery entity — not chemistry substitutes.

Other names

Genuine aliases and pack labels for this battery — not substitutes of a different chemistry.

362 · 361 · SR721W · V362 · V361 · D362 · D361 · SR58

Related codes

Same battery / other names

SR721SW362

Also sold as

Renata/watch-trade 362 → SR721SW

Rechargeables are not equivalents

Do not substitute a rechargeable cell unless the device documentation explicitly allows it. Silver-oxide and lookalike chemistries are not interchangeable with rechargeables by size alone.

Size family

Edge thickness in the 7.9 mm family — thicker bar means thicker cell. Not to scale. Highlighted cell is this page.

1.25 mm

1.45 mm

1.65 mm

2.1 mm

2.6 mm

3.1 mm

3.6 mm

3.6 mm

3.6 mm

3.6 mm

5.4 mm

5.4 mm

Devices using SR721SW

No devices listed for this battery yet.

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Testers & chargers

Optional tools that fit this cell type — only where the chemistry allows. Separate from the battery answer.

Amazon links may earn us a commission. They do not change the battery answer.

Coin cell / button cell battery tester
Quick check of CR / LR / SR button and coin cells before fitting
Buy on Amazon More tools
ZTS Mini-MBT Multi-Battery Tester
More informative state-of-charge style checks across common formats
Docs Buy on Amazon More tools
BT-168D-class digital battery tester
Budget household go/no-go checks
Buy on Amazon More tools

Coin / button cell tester
Quick check for CR / LR / SR coin cells
Open-circuit voltage alone does not prove remaining capacity.
How to test a coin cell Buy on Amazon

Buy links are optional and separate from the battery answer.

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Need a SR721SW?

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Notes

Renata/trade 362 (low-drain 361 ≈ SR721W). Silver oxide watch cell.