This Faithfull Honing Guide is used in conjunction with either an oil, water or diamond sharpening stone to ensure the perfect cutting angle when restoring a cutting edge to straight edged chisels, bevel edged chisels and plane irons from 3mm to 67mm wide. Use the inner jaws for chisels, a blade projection of 30mm will give a 30 degree angle and 40mm will result in a 25 degree angle. Use the outer jaws for plane irons with a projection of 38mm for a 30-degree angle or 50mm for a 25-degree angle.