It wasn't intuitive which size to get and I don't see any guidance here or in the install video as to which size I needed. It lists 12mm and 14 mm, and the ID of my bar is 14mm (technically 13.7mm) so I assumed that meant I needed the 14 mm. But now I see that the throttle binds on the internal white plastic piece that the screw threads into because that piece is 14mm in diameter.