Air Locke Dock Seal's SP and VSP truck seal models inflate down against the top and inward against the sides of your semitrailer or truck, without intruding into the rear opening of the carrier itself. Both models are crafted from neoprene-coated nylon and can be inflated in mere seconds using a 1/10 hp blower mounted directly into the head section. The SP model seals trucks from 12' to 13.5' high while the VSP seals trucks down to 11' high. The VSP model is more versatile as it is constructed with a special head section that enables it to seal a lower carrier as well.