Check the listing for details. Interloc Racing Design Double Roller Drive Headset, 1" Threaded - Silver. Condition: New. Listed at 99.99 USD. Roller bearings for both the upper and lower cups for improved headset performance. Roller bearings offer 3 distinct areas of advantage over traditional round bearing headsets: steering dampening, greater strength, and greater durability. Increased bearing contact acts as a damper absorbing high and low speed vibrations. Roller bearings have a much greater contact area offering increased strength. Load is spread over a great area with roller bearing, reducing pitting and race wear, dramatically increasing durability. Precision CNC-machined 7075 aluminum cups. 1" option uses a 26.4mm crown raceItem Specifications: S.H.I.S. Stem Clamp Diameter, EC30/25.4-24tpi, Color, 29.0mm, Model Name, Double Roller Drive, Weight, Silver, Stack, EC30/26,.