Aluminum Reverse Threaded Coupler for 2.5" SDR smooth-wall innerduct. Sharp buttress-type threads withstand high pulling loads meeting or exceeding the Bellcore tensile standard of 1000 lbs. Machined with a straight thread and long counterbore lead-in for straight, easy starting. Wide eight-pitch thread angle reduces the number of revolutions needed to install the coupling. Smooth exterior wall. Can be used in manholes, direct bury, aerial, or any application except where an air or water tight connection is required. Do NOT install in wet environments, strong acidic/alkaline environments (outside PH 4-8), near salt water, or in concrete.