Auxiliary Key for Entrance: Prevent Leaving Alone ・Dementia measures for the elderly: Wandering prevention ・Preventing young children from opening the entrance door alone ↑Recommended for those who: No tools required, usable in rental properties ⚠️ Purchased used. Opened and used. ⚠️ Please carefully check the dimensions that can be installed in the images before considering purchase. We are not responsible if installation is not possible after purchase. ⚠️ The outer box case has been removed to reduce shipping costs.