6250 - ISO Throttle Boss, use with 6190 & 6240. Added to the popular Küryakyn ISO®-Grips, this little jewel can make all the difference in the world on a long ride. The Throttle Boss™ is a small adjustable paddle that is positioned under the palm of one's throttle hand. This allows the driver to slightly relax the grip on the gas and still maintain a constant speed. Muscle stiffness and fatigue are reduced after prolonged cruising at a steady pace. A new redesigned rubber pad permits use on both grips for a "matched set."