Super-smooth hand controls are the cleanest you can get. Hardware on master cylinders is complitely hidden. Brake master cylinder has a 9/16 bore and can be used with single 2-piston caliper, 4-piston caliper, 6-piston caliper or dual 2-piston calipers. NOTE: we suggest to use DOT 4 brake fluid. in any case do not use silicon based oils.