Bicycle stem wedge - for Tuf Neck and Pro Neck stems Material: 4130 chromoly steel Finish: Black Oxide Fork steer tube inner diameter size: 21.1mm Threading: 3/8" x 16 threads per inch (this is coarse thread - some bolts Tuf Neck used were fine thread. This will only work with a SAE 3/8" coarse threaded bolt which is 16 threads per inch) NOTE: This is a stepped wedge. It will NOT fit a fully ramped quill.