Femplay sells many products like micro vibrators in nipple stimulators and mini vibes that are compact and require a punchy battery without the size. When AAA or AA batteries would simply make a low profile product too large manufactures often to the watch cell batteries suitable like the AG13 also known as LR44 batteries. Most products that use these more obscure battery types contain batteries in the packs, but be aware that even when off this type of battery can drain. There is nothing worse than grabbing your favourite toy in the moment only to find it flat with no spares, therefore we highly recommend purchasing extra batteries and removing batteries between uses. WARNING WARNING If swallowed, a button battery can cause severe or fatal injuries within 2 hours.Keep batteries out of reach of children.If you think batteries may have been swallowed or placedinside any part of the body, seek immediate medical attention N/A