Waterproof Marine emergency cut-off, safety switches attach to your life vest while operating a boat or personal watercraft and are designed to instantly cut battery power when detached. The Magneto (red cap) version functions in applications where the circuit is normally open (not complete) with lanyard clip in place on switch. When lanyard is pulled and clip is removed from switch, circuit is closed (complete), allowing grounding to a suitable ground such as a grounding block, the battery, or a suitable area on the engine itself. Kill switch includes a coiled lanyard that is approximately 15" when coiled and 48" when stretched which should be replaced if worn, cut or frayed. Mounting hole is 5/8" in diameter and can be mounted in a panel up to 5/8" thickness. Maximum 5-amp draw. WARNING: Switch should be tested for proper function before each use.