The RDD27 is a nylon insulated butt splice for wire range #8 AWG. In butt splices, the wires are butted together and crimped at each end of the splice. These splices are color-coded according to wire size. Length 1.69 inches, inner diameter .36 inches and maximum insulation dia .340 inches. The splice is made of high-conductivity electrolytic copper, electro-tin plated. Recommended tools ERG4007 or TBM6S.