M1 Speed Style Mud Flaps by Duraflex. Extreme Dimensions has revolutionized the fiberglass market with our premium Duraflex aerodynamics. Duraflex combines fiberglass, plastic, and flex resins to obtain its unique features. Because of these features, Duraflex technology obtains a much higher durability rate than the average fiberglass product, resulting in reduced shipping damages up to 75%. Duraflex products come complete with black protective coating and high quality mesh grille (where applicable). This revolutionary product allows the consumer to receive a premium fiberglass product at an affordable price.