VW Fox 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.
Before you install your new Fox master cylinder you will want to be prepared to bleed the brake system like the Bentley manual shown below says. Use a high quality brake fluid like ATE Super Blue Brake Fluid to keep your Fox brakes working well in all conditions, and lasting longer.