NMO-1 MOTOROLA "NMO" FEMALE CONNECTOR FOR 3/8" HOLE. COMES WITH CABLE PROTECTOR. NMO-2 NEW AND IMPROVED MOTOROLA "NMO" FEMALE CONNECTOR WITH 3/8" X 24T CENTER STUD. COMES WITH CABLE PROTECTOR AND PLASTIC HOLE ADAPTOR (CHANGES 3/4" HOLE TO 3/8" HOLE). SPECIALLY DESIGNED FOR AM-302 3-WAY MIRROR MOUNT. also FITS 3/8 " x 24T CENTER THREADING HEX NUT FOR 3/8" 24T ANTENNAS.