The stainless steel scraper wire, if needed, is placed next to the roller (drumm wit teeth) to scrape off any food that may get stuck to the roller as it rotates around. The S.S. trip wire shakes the distribution slide when the feeder runs to keep food from bridging inside and clogging at the exit. It also helps portion accuracy and also creates a click clack sound to alert pets at meal time (very liked by most pets) like a slot machine.