Our concave cup wheel may be the most versatile item in the Rockstar line. This super light grinding cup has a curved stainless steel backing coated in pure vacuum brazed diamonds. The unique shape makes it perfect for grinding down lippage in stone or concrete and smoothing out sink openings. This cup is also excellent for quickly removing the fiberglass mesh off of the back of stone slabs. Available in extra coarse (16 grit), coarse (30 grit) and medium (100 grit).