What kind of batteries should I use? カスタマーセンター October 25, 2017 08:33 Updated Follow Please only use Alkaline batteries or else it will cause damage to the NinjaLock. Related articles Can I use manganese batteries? How can I check the remaining battery life? How long is the battery life? I can't figure out how to insert the batteries. Can I attach the NinjaLock onto doors where the thumb turn is combined with the door knob? Comments 0 comments Please sign in to leave a comment.