This is a thick Teflon thrust washer for use between the adjustment nut & the top bushing flange. Easy to install - just remove the cap, handle, and adjustment nut from the axle, drop the washer on, and replace the nut, handle & cap. This washer can serve two purposes - one is to move the adjustment nut to a different position (so your handle isn't over the adjustment screw for easier adjustment). The second - the lubricity of the material between the nut & the bushing flange may enhance the grinding experience. This part is being included with all Pharos as of 9/16/15.