High Visibility! Made of durable 5mm coroplast plastic, this sign is 10″ tall x 28″ long. Specially designed to work with our 7 1/2″ adhesive windshield numbers, this sign is made of black plastic to really “pop” your adhesive numbers. . Sign is held firmly in place by two rubber coated magnets. Note: this sign is not to be used while driving the vehicle.