Zipp SL Speed Stem - 100 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 Defined Color Black Length 100 Material Carbon S. H. I. S. Stem Clamp Diameter 28. 6 Stack