The Master Lock No. 5440D Bluetooth Portable Lock Box. Open and manage with your smartphone or with temporary or permanent codes. Monitor who visits and when through the App and notifications. Removable shackle can be managed with the App or a traditional code. 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.