This guide controls the blade projection when using the Kell sharpening jig.  It is designed for the jig version that has the larger wheel size.  The guide fits onto the jig and fixes the projection of the blade in order to produce a fixed, repeatable bevel angle.  The parametric model and produce any desired angle.  I've provided 25 and 30 deg options or a file that has 25, 30, and 25 with 2 deg microbevel options.   I also have a thin version for narrow chisels and a wide version for normal blades.