Wolf Tooth - Precision Is Integrated Standard HeadsetAny Frame That Uses Is (Integrated Standard) Headsets With 41mm Upper And 52mm Lower Outer Bearing Diameter,Uppers And Lowers Sold Separately,Enduro Stainless Steel Sealed Bearings Included On Both The Upper And Lower,.Upper Assembly Features:Ultralight Stem Cap With Integrated Spacer Plus An Aluminium Bolt And A Star Nut,7, 15 And 25mm Stack Height Top Cover Options (7mm Cover = 8mm Total Stack, 15mm Cover = 15mm Total Stack, 25mm Cover = 25mm Total Stack,O-ring Seal Prevents Water Intrusion Around The Steerer Tube,Custom Moulded Upper Lip Seal Provides Additional Protection For The Upper Bearing,.Lower Assembly Features:Custom Moulded Dual Lip Seal On The Crown Race To Protect The Lower Bearing In The Toughest Conditions.