TCT Machine Countersink & Bores A range of Countersinks and Counterbores. DESCRIPTION A range of Countersinks (part codes prefixed CS) and Counterbores (part codes prefixed CB). Both are 45mm Overall Length and have 10mm diameter Shanks with a flat on one side. Counterbores have length adjusting screw. Available in Left Hand (part codes suffixed LH) and Right Hand (part codes suffixed RH) rotation, and for drill hole diameters 3/16 inch (part codes containing -3/16) and 5mm (part codes containing -5). Please ensure correct variation is selected when ordering. Drills not included in price.