The smart tweezers are operated with alkaline button batteries type L736H or AG3 (dia. 7.8 x 3.4mm). To replace the batteries unscrew the battery and light compartment with a coin on the upper side of the smart tweezers (you see a button with a slot in it). Remove the old button batteries. Insert the new button batteries with the negative side pointing forward into the battery and light compartment. Screw the battery and light compartment back onto the tweezers.