Premier Conduit’s ETL listed Innerduct Terminal Adaptors and Couplers are threaded and made of non-conductive, corrosion resistant anodized aluminum. Premier Conduit’s terminal adaptors and couplers are available in the following sizes: ¾ inch, 1 inch, 1¼ inch, 1½ inch, and 2 inch, which allows them to fit perfectly with common innerduct sizes. These adaptors and couplers are Made in the USA and are HDPE/Riser & Plenum rated for indoor and outdoor use.