An electric strike is an access control device used for door frames. It replaces the fixed strike faceplate often used with a latch (also known as a keeper). Like a fixed strike plate, it normally presents a ramped or beveled surface to the locking latch allowing the door to close and latch just like a fixed strike would. However, an electric strike's ramped surface can, upon command, pivot out of the way when the lock on the door is in the locked position and the door is opened, allowing a user to pull/push the door to open it without operating the mechanical lock or using a mechanical key. After the door is opened past the keeper, the keeper returns to its standard position and re-locks when power is removed or applied, depending upon the strike's configuration. Electric strikes are generally available in three configurations: Fail-secure. Also called fail-locked or non-fail safe. In this configuration, applying electric current to the strike will cause it to unlock. In this configuration, the strike would remain locked in a power failure, but typically the mechanical lock can still be used to open the door from the inside for egress from the secure side. These units can be powered by alternating current, which will cause the unit to buzz, or DC power, which offers silent operation, except for a "click" while the unit is powered. Fail-safe. Also called fail-open. In this configuration, applying electric current to the strike will cause it to lock. It operates the same as a magnetic lock would. If there is a power failure, the door opens merely by being pushed or pulled. A new trend is a strike that is quickly reversible from fail safe to fail secure (and back again if needed). Some manufacturers require the opening of the solenoids, but others allow the reversing of the function within seconds (usually take less than 10 seconds) with only the movement of two external screws or a mechanical unlocking accessory which is directly accessible when the door is open. This is exactly the same principle as a child safety door lock which is installed on car doors. Hold-open. In this configuration, an electric current is applied to the strike, causing it to unlock and remain unlocked until it is used. As soon as the strike has been used, it goes back to standard locked position. This is used in many