I make up a 2 51/64 spacer to hold the level at the proper height to verify wing incidence. I took a 6 inch piece of 1/8 x 2 inch aluminum that I purchased at a local hardware store and bent it 90 degree angle. I then filed one side to exacly 2 51/64" this was clamped to a level to correctly position it over the rear spar web when the front of the level is over the front of the wing spar web.