15 HOLES BUR BLOCKS – Aluminum, Autoclavable – 6 FG Holes, designed for any instruments with FG Shanks (Friction Grip: 19mm) and FGOS (FG Surgical: 25mm) for High Speed Headpieces; 3 RA Holes designed for any instruments with RA Shanks (Right-Angle Latch: 22mm) and RAOS (RA Surgical: 27mm) and 6 RA Holes designed for any instruments with RA Shanks (Right-Angle Latch: 30mm, for polishers with long flame shapes) for Low Speed Headpieces. Dimension: 55mm x 25mm x28/31mm.