The A40 5 term Recessed Single Reed Magnetic Door Contact from Knight Fire & Security is ideal for placement on doors or windows to be wired into your intruder alarm system. When wired into an intruder alarm system, these contacts will triger the alarm and sounder if the opening gap exceeds 14mm. As the contact creates a circuit in your security system, wire tampering or a forced break of the circuit elsewhere will also sound the alarm. What is meant by the tearm Grade 1? Grade 1 refers to the grade of intruder alarm system you have on the premises, especially if you are depending on the alarm system for insurance cover in your home or business. A Grade 1 Alarm basically means Low Risk, Intruders are expected to have little knowledge of the alarm system and may be resticted to a limited range of easily available tools. Please note that this door contact requires a recess in the relevant door or window for installation and cable fitting. Main Features: Flush Magnetic Ree