A proprietary feature developed internally by Columbus. This sleeve works with standard 1-1/8” spacers, offering superior functionality in the form of multiple bike-position tuning variants that allow the users to perfect the fit of their bicycle. 
Compared to the sleeve provided with the Trittico stem, with this sleeve, the rider can adjust the stems geometry to achieve a steeper angulation (-5 Degrees) to improve the fit, handling and aerodynamic position.