... voltage under 4.8V, red light scintilla alarming and you still can open the door.13. Various type, have the ... will be open.Checking working statues: even you are not at home, you can make a call to check the ... to your own demand, just choose the one which you like.More safe: lock core made by stainless steel ... type of the door, very easy and convenient for you to install it on the new door or old ...