7 Pin Heavy-Duty Round Metal Trailer Plug with Internal Weatherbeater Seal and Rubber Boot. Heavy-duty plugs and sockets are manufactured in accordance with the current SAEJ560 standards and thereby meet Australian standard AS 4735-2003 for heavy-duty connectors. Made in the USA the connectors are rated at 40 amp continuous duty and are interchangeable with all other SAEJ560 plugs and sockets.