RING LOCK COUPLINGS ARE SPECIALTY COUPLINGS THAT CAN BE USED FOR WATER, WASTE LIQUIDS, SLUDGE, FISH TRANSFER (ALUMINUM) AND OTHER AGICULTURAL OR INDUSTRIAL WASTES. THEY PROVIDE EASY CONNECTION OF SUCTION/ VACUUM OR DISCHARGE LINES AND ARE TYPICALLY ONLY USED IN CERTAIN STREET SWEEPER, VACUM TRUCKS, OR AGRICULTURAL APPLICATIONS (AS A GUIDE, POSSIBLY COULD BE USED IN SOME PRESSURE APPLICATIONS UP TO 1000PSI ) THERE ARE TWO VERSIONS OF FEMALE, THE STANDARD ARE "ROUND BACK" AS FOR THE MALES, THE STANDARD ARE "NARROW RING" (WILL NOT INTERCHANGE WITH SPECIAL "BUSH HOG WIDE RING MALES" ALTHOUGH THE CLAMPS WILL INTERCHANGE WITH BOTH MALES.)