The Axminster Woodturning long hole boring bit handle uses an ER20 collet to grip the 6.5mm shaft of the Evolution Series long hole boring bit (available separately, order part No. 504581). The handle is hollow, allowing the shaft of the bit to pass through. This useful feature enables you to set a predetermined boring depth, the handle making contact with the tailstock acts as a stop. This prevents the bit coming into contact with your counterbore drive. Fitting an alternative ER20 collet, allows you to use the handle for tools with different shaft diameters.-bg