What is the difference between a single cylinder and double cylinder?
A. A single cylinder has a key cylinder on the exterior and a thumb turn on the interior. A double cylinder has key cylinders on both sides so you'll need a key to lock or unlock the door from the inside of your home. Double cylinders are used on doors with glass panels to provide extra security, but please beware, that in case of an emergency you will have to have the key ready to unlock the deadbolt. The single cylinder version of this product is the Emtek 4811.
