The SR527SW, sold as the 319, is a 1.55 volt silver-oxide watch cell, 5.8 mm in diameter and 2.7 mm tall, holding about 21 mAh. It is the tallest of the common 5.8 mm watch batteries, above the 335, 317 and 379 in the same diameter family.
SR527SW, face and side profile, drawn to scale: 5.8 mm across, 2.7 mm thick.
Voltage
1.55 V
Size (D×H)
5.8 × 2.7 mm
Chemistry
Silver oxide (Ag2O)
Capacity
20-22 mAh
Same battery, other names
Every code below is the exact same cell as SR527SW. Any of them will fit and work identically.
319
Buying and replacement notes
Because four sizes share the 5.8 mm diameter, the 319 is frequently mis-bought. Its 2.7 mm height is the tell: a 379 at 2.1 mm will rattle in a 319 recess and may lose contact when the watch is bumped, showing up as a watch that stops randomly and restarts. Match the code on the old cell exactly.
⚠️ 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
What is the 319 battery equivalent to?
Only the SR527SW; the two codes name the same silver-oxide cell at 5.8 x 2.7 mm, 1.55 V, roughly 21 mAh. There is no common alkaline equivalent in this size, so replace a 319 with another 319 from a reputable maker.
My watch stops and restarts after a battery change. Why?
A too-short cell is the classic cause: a 379 or 317 fitted where a 319 belongs loses contact under shock. Verify the replacement matches the old cell's code and that the retaining clip or strap is seated. Persistent stopping with the correct cell means a movement fault.
How long should a 319 last?
About two to three years in a typical analog movement. Silver-oxide cells hold 1.55 V almost until exhaustion, so the watch runs accurately right up to a fairly sudden stop. Date it with a marker on the case-back paperwork so you know when it was fitted.