Zipp SL Speed Stem - 80 mm, 31.8 Clamp, +/-6, 1 1/8", Matte Black, B2Zipp's SL Speed stem represents the essence of carbon componentry. It's stiff, secure and light weight with a sleek design that compliments any bike. Unidirectional carbon Includes stiff aluminum faceplate and titanium hardware Torx T25 heads for precise torque readings and ease of adjustment Item Specifications Bar Clamp Diameter (mm) 31. 8 Color Matte Black Length 80 Material Carbon S. H. I. S. Stem Clamp Diameter 28. 6 Stack Height 41 Stem Angle