This a Lock Release for door entry intercom and access control systems. This unit is a FAIL SECURE unit for systems that require the door to stay locked in the event of power loss. The unit should be fitted to the keep side of an existing traditional Yale type door lock (known as a night latch) Specifications 12 Volt AC or DC Fail SECURE (Power APPLIED to UNLOCK / Power REMOVED to LOCK) Metal Construction Item is new and unused and contains: 1 x Electric Lock Release WE ARE NOT BOX SHIFTERS If you want PROFESSIONAL quality items that will provide years of faultless, reliable service backed by specialist people who know what they are offering and are prepared to support it..... then this is for you! As with any product purchased from Wholesale Security yo.