Half the secret of sharpening is the control of blade geometry.
Nothing is handier than a bevel gauge for quickly checking the grind angle of chisels, plane blades, turning tools, etc. A quick check confirms the angle last used for grinding or honing so that the edge geometry can be maintained.
Our bevel gauge has seven individual slots that will measure the most commonly used angles from 15° to 45° in 5° increments. Your eye is a fine instrument; it can easily interpolate other angles in the range, angles like 24° or 26°.
The slots on the gauge are about 3/4" deep for good registration. The pocket-sized disc is 2 1/2" in diameter with a center hole for hanging it on a nail.
Made of solid brass, which will not damage a honed edge.