I hope I'm not too late posting this. I found this company and purchased a kill switch for my 120 that does not have a battery. It comes with a little battery pod that will hold 4-AA batteries. It has an on/off switch so the batteries won't just go dead. The remote is like a key fob for your pickup. It has a clip that I used to hook it to my coat zipper, and a small pull out antenna for increased distance.
It seems to work pretty well on these small sleds where there isn't much momentum to keep them moving after you kill the fun.