Harness - Sealco Commercial Vehicle Products Systems can be made for LED lights, incandescent lights, self grounding fixtures or combinations. We have molds for most of the industry standard connectors and a large wire and cable stock to fit your needs. Complete or partial trailer and truck harness designs. Specialty systems can be integrated to match your existing form or harness. Maxi-Seal Products - Maxi-Seal Harness Systems Maxi-Seal Products. Maxi-Seal quality wire harness system is based on our dedication to continuously improve our products and service; providing maximum value to our customers. Maxi-Seals custom-engineered harness system provides the best solution for our customers wiring needs. We offer custom engineered solutions.