LOL, well remote electrical shutoff is not the most common option for "killing", the engine a mechanical shut off of the butterfly via "throttle cut" is probably the most common because it is the simplest and most effcient way to "kill" the engine from a distance.

However, I think I am catching on, and I think you are just talking about the switch that you use to turn your ignition on and off there are tons of options. Most of the main stream manufacturers made HD switches that you can turn your ignition on and off with the mount to the side of the plane. Most of them have a built in charge jack that will allow you to charge your ignition pack right on the side of the plane.

I know that you can get them through any LHS or online supplier like Tower, Chief, Airwild, Dons Hobby, Horizon.... any of those guys.