When a "fail-secure" electric door lock looses power its default position is to lock (or secure) the door. Application of power is required to open (unsecure) the door.
This type of door strike should be used with a good degree of forethought and suitable caution with respect to personnel who may become trapped in the event of a power failure.
Fail-secure door strike - secures door during power outage
Power: 12VDC, 400mA
Dimensions: 128mm x 32mm x 38mm (5.04" x 1.26" x 1.50")