These systems consist of alarm initiating devices, control units, and alarm transmission systems. The initiating device is a switch, operated by hand, foot, key, or removal of currency, that is connected over an electrical circuit to the control panel. Upon activation, the initiating device signals the control panel which evaluates the signal and transmits the alarm over radio or telephone to a remote location if the signal is valid. The system may be used to transmit the alarm to a police station, a central relaying station with means for relaying calls to police, or two or more private stations located within 500 feet of the protected premises and commanding all public approaches to the premises. Three categories of such systems are available: bullet-resisting enclosure and alarm systems, semi-automatic alarm systems, and manual holdup alarm systems. Because such systems entail inherent risks in their use, employers should develop a holdup policy in cooperation with police and the alarm company and instruct employees in the proper use of the system. A robbery deterrent checklist provides guidelines for a security analysis, prevention, and procedures to follow during and after a robbery.