Joker Machine Finned Rear Master Cylinder Cover For Harley Big Twin Give your stock master cylinder a fresh look by changing out the master cylinder cover. Made from billet aluminum and includes all hardware needed for installation. Features Black/silver finish with finned design Fully CNC-machined from 6061-T6 with styling that gives your bike a road-racer look Chrome-plated socket head hardware is included Works with most stock and aftermarket master cylinders