Internal diameter - 44mm Upper - EC44, 55.95mm Lower - ZS56 Upper cup is external (EC) - will fit frames using ZS44 (ZS) upper headcup as standard To suit standard 1 1/8" to 1.5" Tapered steerer tube forks. (28.6 - 39.79) 45 x 45 Degree AC sealed bearings, integrated upper and lower rubber seals. Insertion depth: 9mm Upper, 16mm Lower. Cup Stack height: 3.5mm - Total upper stack height inc bearing cover: 15mm Proudly machined in the UK from 6082 T6, Black Anodize finish Headset comes complete with top-cap (star-nut included), bearings and crown race - all parts required for fitment