Watch Batteries, 12-pack.
Silver Oxide alkaline watch-size button batteries.
These are commonly known as LR44, AG13, 357, L1154, A76, PX76A, 303, D303 and D357. (As long as your toy lists one of these, this is the right item.)
Contains 12 batteries. Most bullet vibrators take 3 of these (Check the label of your toy). Outer packaging may vary.