Proper frame preparation is very important. Park Tool's Head Tube Reaming and Facing Set (33.8mm reamer) combines reaming and facing of the head tube to create a perfect fit for most sizes of head cups. The HTR-1B comes with a reamer of 33.9mm for the 1-1/8 inch headset standard. Includes: - 33.9mm reamer (part #754.2), and four different size pilots (29.8mm, 30.0mm, 33.8mm, and 36.8mm) - 690 Facer - Quick-release, quick-adjust feature: bottom portion slides off and on easily without threading SHIS terminology: The HTR-1B as stock will face frames of EC29, EC30, EC34 and EC37. It will ream frames of EC34. Accessories will allow service in other standards.