Unique idea and nifty engineering. Superb smooth finish in your choice of Color literally in your face. Get rid of the ugly black plastic stock originals. We offer a wide range of reservoir caps to fit clutch, Clutch and Rear clutch Cylinders on a huge range of models. Comes complete with countersunk bolts where necessary. Measurements are the outside diameter. Use your original membrane. Material High Tensile Anodized Aluminum.