If you bleed brakes even once.... this is a must have item to help contain the corrosive brake fluid. It also works well to siphon old fluid out of the master cylinder reservoir.
Very easy concept for bleeding brakes quick and easily. Get a gallon of Denatured Alcohol at a home improvement store for super easy cleanup. Just rinse it out with the alcohol.... that easy. I'll be buying the second cap I need for my other cars.