I just purchased but have not yet installed an MOB+ engine cutout switch. It pairs with a fob that activates on contact with water. My primary use case is for one-handing, which I do a fair amount of, positioning the boat ahead for wife and family to join and such. I have a mental movie of going over the side when stepping out the pilot house door to attend to something on deck while the boat is on autopilot and watching it chug off into the distance. I plan to zip it into my PFD, which also has an inflation activated AIS beacon and strobe looped in. But it can also be worn on a bracelet by a child or a collar by a pet.