Fire Door Retainer.
A wireless solution for legally holding open fire doors. New SmartSound technology - not triggered by vacuum cleaners. Three-year battery life and three-year warranty. Carpet friendly - leaves no marks. Can be fitted to most types of doors. No programming required, just fit and forget. Installed easily in under five minutes. Set Dorgard SmartSound to release the door automatically. Set your Dorgard SmartSound to release your door at the same time each day.