RS Nylon Insulated Crimp Ring Terminals Nylon insulated copper crimp ring terminals with a copper sleeved double crimp barrel. These insulated crimp ring connectors are Color coded for use with different wire ranges and are available with various stud sizes. For suitable crimp tool see stock number 267-3133. Red 0.5 - 1.5 mm2 Blue 1 - 2.6 mm2 Yellow 2.5 - 6.5 mm2