Upgrade Your Brake System: Our electric trailer brake kit includes 4 brake assemblies, designed for trailers and RVs with tapered axles up to 10000 lbs. 12.25 x 3.375 inch brakes, with 7 holes on a 5.5 inch bolt circle, fit most vehicle installations Automatic Brake Adjustment: Forget constant brake checks! The trailer brake kit adjusts automatically to maintain the perfect brake gap, avoiding wear and keeping your system responsive for long-term use. Ideal for frequent braking and long trips Easy Installation: Installing your new brakes is a breeze! Our self-adjusting electric brakes it comes pre-assembled with core parts installed. Just add oil, follow the easy steps in the manual, and you're good to go Stable Braking Under Heavy Load: Upgrade to semi-metallic brake pads with a 0.48 friction coefficient (GG level). Our trailer brake are heat-resistant, durable, and reduce noise—fit for heavy-load, downhill, and frequent braking ≥30000km Lifespan: These steel brake assemblies of the self-adjusting electric brakes kit are shock-resistant and built to last. The protective shield keeps debris out, securing your system and ensuring it lasts longer, even on bumpy roads