I have a snapon kit and its called (10 pieceScrew extractor set)
I have owned it for about 8 years and I remember being suprised at how little it cost when I bought it.

It has payed for its self time and time again.

If I remeber correctly the smallest one even fits in the ignition rotor bolts and thats worth the cost rite there.

The chances are if you get it you will use it again in the future.

It workes even if the recess is totaly rounded out. You just tap it in and the more torque you put to it to remove the bolt the harder it bites in.

GL......................Dave