Toolmaster high speed steel adjustable hand reamers can be set to any size within the specified range of the reamer and are commonly used for odd size holes as well as when accuracy is required. <b>How to adjust & measure size:</b> To increase size: Loosen & unscrew rear locking nut closest to drive shaft while holding blades from slipping out, now screw & tighten front locking nut allowing blades to slide along the slots in the main body until blades meets rear locking nut to secure blades into position. To reduce size: Loosen & unscrew front locking nut while holding blades from slipping out, now screw & tighten rear locking nut allowing blades to slide along the slots in the main body until blades meets front locking nut to secure blades into position. To measure required size: It is very important that you measure diagonally across two opposing blades and on the cutting edges to get an accurate reading. This is a Hare & Forbes special-order item, available to order through Alltools Geelong (order code R743) for collection in store.