Servicing Pin will silence the sounder units within the Protective Covers during transit, installation and during any maintenance work that may be carried out on the manual call point. (Supplied with Euro Stopper Sounder Models, Universal Stopper Sounder Models, Enviro Stopper Sounder Models, Stopper II Sounder Models and the Mini Theft Stopper.) NB: This needs to be retained after initial installation so that the alarm can be silenced during servicing to protected device.