This is a child lock that attaches to door knobs. It has a lock button. It helps prevent babies and pets from opening doors. It can be installed later and is easy to set up. Uses 3M adhesive tape & can be removed without leaving marks. Size is approximately: Door lock: 7.2*3.5*7cm when opened 90 degrees Door lock release: 2.5**3.5*7cm when rotated 180° Although unused, it has been in someone else's possession. Instant purchase is welcome, but please understand that this is a personal inspection/storage item, so please only purchase if you understand. #DoorLock #DoorKnobLock #PetEscapePrevention #ChildLock #BabyGuard