Description: Bike Fork Headset Base Compression Ring Conversion Adapter Bottom Spacer Made of qualified aluminum alloy and steel, sturdy and durable to use. Useful accessory for bike lovers to maintain their bikes. Easy to install and carry. Different front forks are matched with different washer, so the base spacer style are different. Specification: Material: Steel(B/C), Aluminum Alloy(A/D/E/F/G/H) For Spacer: A-34/44mm Bearing Spacer; B/C-44mm Ball Spacer; D/F/G/H-52/55/56mm Bearing Spacer; E-50.6mm Bearing Spacer For Front Fork: A/B/C/D/H-Straight Tube Fork; E-1.25inch Small Cone Tube Fork; F/G-1.5inch Cone Tube Fork Size: (mm) Inner Diameter 29.8(A) 29.8(B) 29.8(C) 29.8(D) 32.9(E) 39.8(F) 39.8(G) 39.8(H) Outer Diameter 39.9(A) 39.8(B) 38.4(C) 50.5(D) 45.8(E) 50.4(F) 59.9(G) 59.9(H) Thickness 4.4(A) 4.4(B) 5.7(C) 4.5(D) 7(E) 4.4(F) 6(G) 6(H) Package Includes: 1 Piece Bike Headset Base Spacer(2 Pack) Note: Color might be slightly different due to the color calibration of each individual monitor. Please allow slightly measuring deviation due to manual measurement.