Headset tensioning top cap Carbon fork expander 1-1/8 inch system for use in carbon composite steerer tubes. Expands inside the steerer tube. Causes no scoring or marking inside the steerer. Recommended for carbon composite steerer tubes. Anodised black finish with a lacquered carbon fibre top cap. Great looking and extremely functional. Look after your carbon road forks with a M-Part Carbon fork expander 1-1/8 inch.