Simple end stop adjuster so you don't have to play with the annoying bed screws to set your 1st layer height. Tram (level) you bed with the nozzle, don't worry about height. get it planed correctly, then use the adjuster to set the nozzle height for that perfect 1st layer without ever touching the bed screw again. Adjust in again and again for different materials, or change of nozzles, what ever. Use the adjuster to set the height, not the bed screw.