The Internal Throttle Assembly from Exile Cycles is absolutely essential for any self-respecting custom bike. The unit installs in the end of your handlebars eliminating any visible throttle housing and allowing the throttle cable to be routed inside the bars for that super-clean look. This is our STANDARD internal throttle and the twist-sleeve standard diameter matches that of the stock Harley Davidson plastic throttle sleeve. This unit works with any grip that fits over the stock throttle sleeve, as almost all rubber grips do. The Internal Throttle Assembly is generally supplied for use with stock 1" handlebar tubing, but other handlebar insert diameters can be requested by calling 818 706 1230. Made in the USA and beautifully engineered with a smooth, roller-bearing action, this kit is the best available.