The ATC contact transmitter a microprocessor-controlled radio transmitter for alarm signals generated by three types of contacts: “cord" contacts with digital counting of programmable impulses, inertial contacts with trimmer-adjustable sensitivity, external NC magnetic contacts or bypassable internal reed bulb. if activated by magnetic contacts, transmission occurs upon either opening or closing of the contact and contains information on the status (open/closed). The unit identifies individually activation of each input Radio range: 300 m in open field; external directional antenna can be connected (see accessories). Preset for recessed inertial sensor mod SD1.