Whatever kind of watch you have, it's likely that one of these silver oxide button batteries can power it.

Specification

Product
Product id	590348
Brand	Duracell
Partnr	5000394067790
EAN/UPC code	5000394067790
Battery
Battery type	Single-use battery
Battery size	SR60
Features
Battery technology	Silver-Oxide (S)
Battery form factor	Button/coin
Battery voltage	1.5 V
Number of batteries included	1 stuk(s)