If the Calipers need to be replaced on your 3,500lb Trailer Disc Brake Setup, this is an ideal and high-quality replacement for the Left Hand Side of your trailer. The Trailer Disc Brake Caliper is Zinc Plated for corrosion protection, and is typically fitted with 5 Lug Integral or Slip Over Style Trailer Disc Brake Rotors that measure 9.75" in diameter. The Caliper Comes Pre-Loaded with Pads already installed, and features Stainless Steel Brake Pad Guides, a Hard Chrome Plated Piston, and Stainless Steel Anti Rattle Clips for quiet trailering and braking.