Master 5406D compact portable lock box. Designed to lock over house door knob. 2 3/4" wide lock body with a 13/32" diameter shackle with 1 13/32" clearance. Shackle is vinyl coated to protect door knob. Inside measures 1" high x 2 1/4" wide by 3/4" deep. 3 dial combination that can be reset to your number. Dials protected by cover. Holds up to 3 house keys.