Use your smartphone to open and manage your lock with the Master Lock® safe system compatible with both Master Lock Vault Home and Master Lock Vault Enterprise app (ios & android). Monitor and grant access, with alerts for tampering and low battery. Metal lock body for durability, boron alloy shackle provides maximum resistance to cutting and sawing. Bluetooth authentication and military-grade encryption. Directional backup code for emergency access without a phone. 1 CR2450 Battery included. 57mm thick metal housing and bracket diameter of 9mm, bracket has a vertical clearance of 51mm.