The 381 watch battery, also known as SR1120SW (IEC code SR55), is a 1.55V silver oxide button cell about 11.6mm across and 2.1mm high. The 391, also known as SR1120W, is the same size. This page brings together every 381 and 391 battery we stock, all genuine Japanese cells from Maxell, Murata, Seiko and Seizaiken.
Choose the SW version for an ordinary analogue watch with a low power draw, and the W version for watches that use more power, such as models with alarms, lights or chronographs. If in doubt, replace like with like and match the code on the battery you took out.
UK delivery is free on every order.
