PCD SEGMENTS - PCD clockwise segments allow longevity and higher productivity on rougher surfaces such as thick mastics, glue, paint, VCT PCD & SET - PCD clockwise includes 3 grinding discs for Iron Horse, Warrior, XtremePolishing & ASL planetary grinders NON-THREADED HOLES - 3 x 8.5mm non screw holes designed for grinding machines with 3 non threaded holes for the RTS Iron Horse Grinders USE WET OR DRY - walkbehind grinder recommended Trapezoidal diamond grinding tooling with 3 x 8.5 mm non-screw holes designed for floor grinding machines with three non-threaded holes, including variants with magnetic plates. PCDs are ideal for aggressive removal of epoxy, paint, glue, mastics, and coatings. Not to be used directly on concrete and any metal material. Clockwise direction, comes in a set of 3 pieces. Use wet or dry with Iron Horse Planetary grinders such as RTS /750-T9/650-T8/600-T1/550-T7/500-T2/T3/460-T6 or Warrior, XtremePolishing & ASL floor grinders.