Barrier materials furnished under this specification are intended for application to plane and curved ship structures and machinery surfaces in order to attenuate airborne noise. Type I material is the top or middle layer of thermal, acoustic, or fire insulation materials which are attached to the deck, bulkhead, overhead, or machinery easing surfaces. Standard application details are contained in Naval Sea Systems Command (NAVSEA) drawings 804-5773931 and 804-5773932. The type II material (see 1.2) intended as middle layer (sandwich) components of composite treatments use an insulation material for the lower layer and a faced panel or metal sheathing as the upper layer. Type II treatment is used where Coast Guard approval is required.