This adaptor is made from high quality chrome plated brass and has one internal 1” – 14 TPI thread and one external 1 1/4” – 11 TPI thread. The adaptor can be used to convert an external 1" 14TPI thread to an external 1 1/4" 11TPI thread. The external thread fits the N240F revolving nut which is supplied with many of the AC Antennas products.