Lightweight, precision sealed bearing alloy headset for use on 1" threadless system forks.
ISO standard type sizing.
 
Features
Aluminum Headset cups 
Sealed cartridge angular contact bearings
Star nut and aluminium Top Cap included 
Size: 1" ISO
Colour: Silver or Black anodised
 
Specifications
Upper stack height: 14mm
Lower stack height: 11mm
1" ISO specification sizing:
Crown race: 26.4mm
Headtube ID: 30.2mm
Fork steerer OD: 25.4mm
Note: Please pay particular attention to the diameters, as 0.2mm is a significant difference. 
Installing an incorrect size part will damage frames or forks.
Do not use Star Nut insert on Carbon forks.
Seek assistance from an experienced Bicycle mechanic if in any doubt