9x9mm Square Holder for 6mm Dia. Boring Bar The longitudinal slit in the square holder allows it to compress and clamp securely onto round shank tools such as boring bars.Bore Dia.: 6mmSize: 9x9mmLength: 55mm 11x11mm Square Holder for 8mm Dia. Boring Bar The longitudinal slit in the square holder allows it to compress and clamp securely onto round shank tools such as boring bars.Bore Dia.: 8mmSize: 11x11mmLength: 65mm 13x13mm Square Holder for 10mm Dia. Boring Bar The longitudinal slit in the square holder allows it to compress and clamp securely onto round shank tools such as boring bars.Bore Dia.: 10mmSize: 13x13mmLength: 70mm 15x15mm Square Holder for 12mm Dia. Boring Bar The longitudinal slit in the square holder allows it to compress and clamp securely onto round shank tools such as boring bars.Bore Dia.: 12mmSize: 15x15mmLength: 80mm