This is a small outboard motor kill switch key, however, it will fit any kill post which is about a centimeter in diameter and 5mm out. So I suspect it will fit a lot of wave runners and jetski's as well. Updated with a stronger back and slightly more forgiving angle for insertion.

9/15/2015 update: A couple of people have asked what this will fit on. I made it for a Nissan outboard, but have used it on a Polaris Jetski, and with a bit of heat and some time with a pocketknife used one on a Yamaha waverunner. What I guess I would ask, is since it clearly has been downloaded a lot of times, it would be wonderful if those people that use it for something, actually comment with the brand and model Something like "Yamaha 2001 GP1200R" would be great... Thanks!