Impact sensitive Fuel cutoff switch?

Any body know who makes them or who sells them? I remember seeing them a number of years ago to shut off electric fuel pumps in a hard crash. Seemed like a good/safe idea. Any comments? couldn't be much of a problem in a street car, but a race car (non drag) might be more problems then it solves?

Ron Francis has them, and yes they are a excellent thing to have.

http://www.parts123.com/parts123/yb.dll?parta~dyndetail~0000278a~AAAOB~77.50~~~~1GN00O92K~

-Jon

On Efi vehicles its called an inertia switch, typically a magnetic switch with a spring trying to seperate the contacts if its shocked hard enough it opens..generally good, but sometimes slamming a door or trunklid will open it as far as on a race vehicle if the car hooks good the violence of the launch can cause the switch to open

They've been on Fords since they went to EFI, and are generally mounted in the trunk, away from the tank & electric pump; might be adaptable to an aftermarket pump.
To be honest, it's not something I've worried about; there's a switch on my dash and a master cutoff on the rear of the car per NHRA rules. But if no-one's around & your bell is really rung, an impact-switch could be a nice thing to have. I guess the thing to find out is at what impact the Ford unit activates; I can tell you that I once hit a chunk of tire on the freeway that whacked the LR wheelwell of a Ford I was driving and shut the pump off. So I think it was fairly sensitive.

the belt parkway in brooklyn can cause them to open, especially when going over a draw bridge. Don't ask me how I know.