Promax MA-504L 31.8mm Length 100mm Adjustable Threadless w/Light Mount BlackPromax MA 504L 31. 8mm Length 100mm Adjustable Threadless w Light Mount Black. The MA 504L adjustable stem lets you quickly change the handlebar height then holds it securely in place for better comfort and control. An integrated mount also gives you an easy way to add some light when the sun goes down. Adjustable Threadless design with Light Mount Aluminum construction Angle range: 90 160 deg TECH SPECS Bar Clamp Diameter (mm) 31. 8 Color Black