Uniquely-designed self-contained unit providing a simple and effective way of retaining and releasing fire doors safely and legally. Will hold open fire doors which are fitted with a door closer but will safely release the door should the fire alarm sound. Simply attach the unit to the base of the door and push the plunger downwards to hold the open door in place. Supplied with 2 C batteries, instructions and fixings. Requires no wiring or mains power. Can be installed in under 5 minutes Complies with all relevant European Directives and UK Workplace Regulations. Each.