This is a 4/0 AWG stranded connector with a 3 inch body and a 0.90 in (22 mm) O.D., that are for splicing applications on aluminum or copper cable products
The 3M™ Connectors CI Series are for splicing applications on aluminum or copper cable conductors. The aluminum connectors CI Series are specially designed for use with 3M™ QS-I, QS-II and QS-III pre-molded power cable splice bodies. These connectors meet the requirements of ANSI C119.4.