This is a Crowtail compatible magnetic switch module. It is based on encapsulated dry reed switch MKA14103. MKA14103 is single-pole, single throw (SPST) type, having normally open ruthenium contacts. The sensor is a double-ended type and may be actuated with an electromagnet, a permanent magnet or a combination of both. The magnetic switch is a wonderful tool for designers who would like to turn a circuit on and off based on proximity.