S7 is what jackhammer bits are made out of. <img src="/ubbthreads/images/graemlins/eek.gif" alt="" /> And that’s “regular” S7, not SR77. <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" /> That’s why they’re so tough and have no problems with concrete blocks. You could probably chop up your sidewalk if you wanted. <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" />