Take your stopping power to the absolute maximum with the Juin Tech GTP4 4-Piston Cable-Actuated Hydraulic Disc Brake Caliper Set. If you ride a Post Mount Road, Gravel, or Cyclocross bike and need heavy-duty braking performance without the expense of upgrading to full hydraulic STI levers, the GTP4 is your ultimate solution. The 4-Piston Advantage: Unlike standard 2-piston calipers, the GTP4 features a quad-piston closed hydraulic system. When you pull your existing mechanical brake lever, the cable actuates all four pistons simultaneously. This provides a significantly larger pad contact area, resulting in massive stopping power, ultra-smooth modulation, and exceptional heat dissipation. It is perfect for aggressive riders, heavy touring loads, or anyone who demands the best braking performance available. Why Choose the GTP4? Maximum Stopping Power: The 4-piston design offers superior braking force compared to standard 2-piston mechanical or hybrid disc brakes. Cost-Effective Upgrade: Keep your current mechanical drop-bar levers and shifters. Zero Bleeding Required: The closed system comes pre-bled with mineral oil from the factory for a clean, fast, and hassle-free installation. Product Specifications: Model: Juin Tech GTP4 Brake Type: Cable-Actuated Hydraulic Disc Mount Type: Post Mount (PM) Piston: 4-Piston (Quad-Piston) System Fluid: Mineral Oil (Pre-bled) Weight: Approx. 135g per caliper Compatibility: Road, Gravel, CX (with Post Mount) *Note: Please verify that your bicycle frame and fork use the Post Mount standard before purchasing. IS mounts will require an adapter.