VW master cylinder. We only carry original equipment quality, direct fit master cylinders; you don't ever want to skimp out on brake components. The master cylinder is responsible for converting your foot pressure into stopping power for your vehicle. If your brakes feel spongy, or the pedal is progressively getting softer it is time to replace your master cylinder, before your car no longer stops at all.
This VW master cylinder does not include a new reservoir. A new reservoir may be what you need if you find the one in your Golf, Jetta or Passat is cracked, or if it is dirty and contaminated. This will make sure you don't contaminate your new fluid. Flush fresh brake fluid through your brake lines when you change the master cylinder. Never try to reuse old fluid; over time it draws moisture from the air and then it can't handle the heat generated while stopping.