Park Tool 788 Reamer: 43.95mm

Reams head tube I.D. to 43.95mm to accept "internal" headset cups with 44.05 - 44.10mm O.D. (1-1/8 ZS standard) Use the 788 with the 690-XL Facing Cutter and 750 Centering Cone For upper or lower headtubes that accept the ZS44 or EC44 headsets to 43 95mm to accept "internal" headset cups with 44