Zoom Adjustable A-Head 1 1/8" Bike Stem - Black - 100mm A-Head style fitting - where the stem fits around the fork steerer (common with modern Hybrid, Road and Mountain Bikes) 100mm length (measuring from the centre of the steerer clamp to the centre of the handlebar clamp) 31.8mm handlebar clamp size 1 1/8" steerer clamp size (the clamp for the fork tube) Stem is alloy with steel bolts