SpringLOCK is a market leading system to prevent unwanted removal or loss of artwork. Locks are pushed into position and can only be removed using the special release tool. This listing offers the following items: Method A Pack (Side by side installation) Pack includes two springLOCKS (i.e. two bridges and two locks) and four screws. Method B Pack (Two top hangers and bottom lock) Pack includes two hang plates, one springLOCK and six screws. You may also need a Release Tool to release the lock and Marker Buttons which fit into the bridge to assist with marking wall screw positions.