Abstract: A fire or smoke barrier has a head box, a drum holding a curtain and a bottom bar for weighing the curtain. A stop mechanism includes a series of stops preventing the bottom bar of the curtain from descending. The stops being connected together, and held in non-deployment position. The barrier also includes a release such that in the event of a fire the stops can be withdrawn from their position by pivoting out of the way of the bottom bar either in the plane parallel to the bottom bar, or by rotation about their end to a position 90° to their original position. The release includes a handle to move the stops, and may include a spring to withdraw the stops. In addition the release includes thermal links which fail on temperature rise to allow a spring to move the stops away from the bottom bar resulting in deployment of the curtain.