Hydro-Flex non-insulated flex duct is designed for strength and durability.  This reinforced flex duct is constructed with a spring steel wire helix encapsulated in a tri-laminate consisting of metalized polyester, a layer of scrim reinforcement for added strength, and a black pigmented inner-surface (non-reflective).  Four (4) heavy-duty duct ties are included in each non-insulated package giving the convenience of four connections.