Left hand slow spiral flute, right hand cut taper pin (1/4” per foot) hand reamer with square drive. Designed to convert a straight hole into a tapered hole into which standard taper pins (ASA B5.20-1958) will fit. The square on the shank is suitable for holding a tap wrench or vise, depending on whether the reamer or part is rotating, making them ideal for hand use. Recommended for most materials. Produced per ASME B94.2-1995 standards.