The Master Lock No. 4400EC Bluetooth® Padlock features a 1-29/32in (47mm) wide metal body for durability. The 9/32in (7mm) diameter shackle offers 7/8in (22mm) vertical clearance and is made of boron alloy, offering maximum resistance to cutting and sawing. Secure your home or business with the Master Lock Vault System for unmatched security, simplicity and accountability using the latest in Bluetooth lock technology from Master Lock. These locks withstand physical attacks and hacks, protecting your property with military grade encryption and high-security features. Administrators control individual or system-wide lock access with our convenient app and web interface options, while users enjoy simple, secure access to assigned locks or lock boxes.