Killark ZS311CR - Nylon retention ring for increased holding power. Neoprene bushing seals against moisture. Nylon connectors obtain approximately the same retention values as metal cord connectors Nylon retention ring for increased holding power. Neoprene bushing seals against moisture. Nylon connectors obtain approximately the same cord retention values with hand tightening that can be produced only by wrench tightening of metal cord connectors. - Durable nylon construction makes these connectors perfectly suited to corrosive environments. Typical applications for nylon cord connectors include food processing facilities, chemical and sewage treatment plants, and off-shore and dockside installations