These are MC4 "U" UL Approved Branch Connectors. This one is has Two MC4 Female Connectors and One MC4 Male Connector. These are used to connect multiple solar panels or groups of solar panels together in a solar field. The unique design offers greater directional ease in laying out the the branch lines. The molded in eyelets allow for easy tie wrapping of the branch connectors to the structure. Shipping weight is 2 oz.