Upgrade your trailer's braking and sealing system with this all-in-one heavy-duty kit from Trailer Supplies. This set includes two pairs (4 pieces) of self-adjusting electric brake assemblies, sized 12-1/4" x 5", engineered for 12,000–15,000 lb trailer axles. Also included are four unitized oil seals measuring 3.125" inner diameter by 4.50" outer diameter, built for use with Dexter 10K–15K axles and compatible with select AL-KO and Rockwell axle models. Each brake assembly comes fully pre-installed with high-strength shoes, magnets, springs, and a durable backing plate—ready to mount to standard 7-hole flanges. The self-adjusting design maintains proper clearance between the brake shoe and drum for reliable, low-maintenance performance over time. The included oil seals feature a double-lip, unitized structure with NBR rubber sealing surfaces and reinforced steel casings. They provide a secure, leak-resistant fit to help retain bearing grease while shielding your hub system from water, dust, and debris—ideal for trailers exposed to harsh conditions and heavy-duty use. Whether you're servicing livestock haulers, flatbeds, or commercial equipment trailers, this combo offers a dependable, OEM-compatible solution to keep your axles performing at their best.