For indoor or outdoor use; Wall mount lock box is best used for key and access card storage; Large internal cavity allows secure storage for multiple keys; Weather resistant to -40° Share temporary or permanent access via Bluetooth or keypad code with invited guests (Wi-Fi connection is not required to operate); Monitor activity, and receive tamper and low-battery alerts Ideal for use on Airbnb and VRBO vacation rental properties, unmanned remote locations, and real estate Master Lock Vault Home and Enterprise Apps are designed for personal use, supporting up to 10 locks. Can be upgraded to Master Lock Vault Enterprise business platform, and integrated with ShowingTime and BrokerBay scheduling management 3-1/4 inch wide lock body; Internal dimensions 3-39/64 inch height, 2-1/2 inch width, 1-7/64 inch depth; Replaceable CR123A battery (included) For answers to frequently asked questions, troubleshooting, and technical support, see document titled User Guide in the technical specifications section of this page