You can reuse the "O" ring a few times with no problems. The new style is a flat fiber composition with a silicone bead for sealing. They work well too.

 

I have the Craftsman's too, I also have the Lisle brand easy outs, both work great (in the right hands)!

 

just wanna add,,,,,,, there are left hand twist drill bits out there,,,, as you drill
the bit catches and spins the stripped bolt out,
keep that in the back of your mind, its a good way to prevent buggering anything up