Park tool head tube reaming facing set htr1bproper frame preparation is very important the htr 1b combines reaming and facing of the head tube to create a perfect fit for most sizes of head cups htr 1b comes with a reamer of 33 9mm for the 1 18 inch headset standard 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 featuresincludes 33 9mm reamer part 754 2 and four differen