The right side one (throttle side) has a plunger inside that as you turn the end back (toward you) as you add throttle it tightens and locks the throttle in one place. It does take some time using it to really be smooth. But, you can just push the throttle forward and it automaticly releases any friction, which I really like. For me I always leave my hand draped on the throttle with my fingers over the brake lever. I never pull my hand off (except to scratch my nose
