The Vtg Ray Jefferson Security Guard Model SG-1 Marine Boat Alarm System Pair is a set of alarm systems designed specifically for marine boats. These alarm systems, featuring the Ray Jefferson SG-1 model, are designed to provide security and protection for marine vessels. With a focus on surveillance and alarm equipment, this product falls under the category of sirens, bells, and alarm speakers, ensuring the safety and security of boats and their valuables. Note these are not tested. They both have a plunger type switches. One with a back and one without. The sg-1 switches one of them has 2 toggle switches attached and a 9 volt battery terminal . I am not really sure what they are but they appear to be in good condition but are as is