Eastern Sheet Metal Dual Wall Oval Spiral Pipe and Fittings are available in the same wide ranges of sizes our our single wall oval. Like our single wall offering our dual wall is available with slip connections and Eastern Flange connections and in the same side variety of materials. ESM can provide any combination of inner walls, perforated or solid, we prefer solid inner walls for fittings and perforated inner walls for spiral duct, along with several types of insulation. We can provide our standard fiberglass, ductliner or our own E-Free insulation with a polyester rayon facing to keep fiberglass out of the airstream.