Replacement cutter heads for 7/8 in. Diameter or larger. At last, the answer to drilling through concrete-embedded rebar! No more broken or shattered hammer bits; now you can drill through the rebar and not have to relocate the hole to avoid the rebar! Used to cut holes through embedded steel reinforcing bar. It is used to prevent damage to the hammer bit, which occurs if the hammer bit is used after rebar is encountered.