STI 1230 Stopper II Surface Mount(50mm Spacer) Call Point Cover Without Integral Sounder helps prevent malicious or accidental false fire alarms. The Stopper II is a unique device that has helped prevent false fire alarms around the world for more than 30 years, without restricting legitimate operation of devices such as fire alarm break glass call points. It is ideal for schools, colleges, hospitals, nursing homes, hotels, and all public buildings where there is a history or a threat of false fire alarms.