The 40-Series is the work-horse of Cane Creek's headset line-up and incorporates all the features necessary for a durable, light-weight, long-lasting headset while offering the perfect balance of performance, durability and value
Features:

Contoured and relieved 6061-T6 aluminum for minimized weight and maximized strength, with split-lip sealed stainless steel bearings
Low friction, Dual-Seal crown race and top cover provides maximum sealing from contaminants, plus a captured compression ring design for carbon steerer compatibility (Interlok spacer compatible, sold separately)
Cane Creek ZS (Zero Stack)
Internal parts are cross-compatible across the 10, 40 and 110 series

Specifications:
Technical Description: ZS44/28.6/H8/K|ZS44/30/H4/K
Top Type:ZS - ZeroStack
Top Head Tube Inside Dia.:44.00mm
Stem Clamp Dia.:28.6mm
Top Stack Height:8mm
Top Bearing Type: Black Oxide, Sealed
Bottom Type:ZS - ZeroStack
Bottom Head Tube Inside Dia.:44.00mm
Crown Race Seat Dia.: 30.015mm
Crown Race Type:Steel, Face-Sealed
Bottom Stack Height:4mm
Bottom Bearing Type:Black Oxide, Sealed
Material:6061
Weight: 88g