De Luxe forged hand controls feature a smooth and compact design, and are just perfect for any old school project. Hydraulic clutch master cylinder features forged aluminum body and clamp, finned master cylinder lid and forged aluminum lever for a true old school look! Hydraulic clutch master cylinder has a 9/16 bore. For 1″ diameter handlebars. NOTE: we suggest to use DOT 4 brake fluid. in any case do not use silicon based oils.