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Silver-oxide watch (SR)

SR927SW battery: equivalents & specs

The SR927SW, sold as the 395, is a 1.55 volt silver-oxide watch battery, 9.5 mm across and 2.7 mm tall, with about 55 mAh. Its high-drain sibling, the 399 (SR927W), is the standard cell for many quartz chronographs including numerous Seiko and Citizen models.

SR927SW battery drawing: 9.5 mm across, 2.7 mm thick SR927SW 1.55V + ⌀ 9.5 mm 2.7 mm
SR927SW, face and side profile, drawn to scale: 9.5 mm across, 2.7 mm thick.
Voltage
1.55 V
Size (D×H)
9.5 × 2.7 mm
Chemistry
Silver oxide (Ag2O)
Capacity
52-57 mAh

Same battery, other names

Every code below is the exact same cell as SR927SW. Any of them will fit and work identically.

395SR57V395SR927W (399, high drain)

Compatible replacements

  • LR927 / AG7: Alkaline same-size cell for toys and novelties; not a watch-grade substitute.

Buying and replacement notes

If your watch has stopwatch subdials, check its manual before buying: many chronograph calibers specify the 399 rather than the 395, and the difference shows under load. The 395 remains the right cell for simple analog watches in this size. Both share the 9.5 x 2.7 mm case, so the risk is not fit but performance mismatch.

Commonly used in

analog watcheschronographs (399)sports watches

Need a replacement?

Shop SR927SW batteries on Amazon →

Comparisons

LR927 vs SR927

⚠️ Keep away from children. Swallowed button batteries, especially 20 mm lithium coins, cause severe injury within hours. If a child swallows one, call the 24/7 National Battery Ingestion Hotline (US) at 800-498-8666 or poison control at 800-222-1222 immediately. What every parent should know.

Frequently asked questions

Is the 395 the same as the 399?
Same dimensions, different drain design. Both are SR927 silver-oxide cells at 9.5 x 2.7 mm and 1.55 V. The 395 (SW) is for low-drain analog watches, the 399 (W) for chronographs and feature watches with pulse loads. They interchange physically.
Which battery does my quartz chronograph need?
Most likely the 399 if the old cell carries that number or SR927W. Chronograph stepper motors draw sharp current spikes, and the 399's electrolyte is formulated to hold voltage through them. A 395 will run the watch but can stall the chrono hands.
How long does a 395 last in a watch?
Two to three years in a simple analog movement, thanks to its healthy 55 mAh capacity. In a chronograph running a 399, expect closer to two years, less if you use the stopwatch heavily, since timing functions multiply average current draw.

More Silver-oxide watch (SR) cells

SR416SWSR512SWSR516SWSR521SWSR527SWSR616SWSR621SWSR626SWSR716SWSR721SW