Master Lock · Lock Box · Commercial · Residential · Digital.Master Lock 5441D 3-1/4″ Electronic Bluetooth Wall Mount Lock Box – Open and manage with your smartphone or with temporary or permanent codes. Monitor who visits and when through the App and notifications. Easily installed using hardware supplied with the lock box. Large capacity to hold key cards or traditional keys. Long life battery is easily replaceable. Solid body durability and coated surface to protect hardware and door finish. Works with the free Master Lock Vault eLocks App.