Features: *No lock hole design, it completely abandons the traditional key and lock, in the fully opened and closed by remote control or phone APP, realized the real security. *Extended antenna, stronger signal, safer and more responsive. With BT adapter, can achieve lock/unlock by phone APP. *Add USB external power source function. Make sure the lock works when battery was dead.(batterynot included) *Three unlock modes optional: Phone APP unlock, Remote control unlock, indoor button unlock. *Easy installation on all kind of doors, very convenient.