RS Insulated Crimp Ring Terminals A range of insulated crimp ring terminals made from copper with flared vinyl or nylon (mini-yellow) insulation. These insulated crimp ring wire connectors are Color coded for use with different wire sizes including Mini Yellow 0.2 - 0.5 mm2 and are available with a variety of stud sizes. Mini Yellow 0.2 - 0.5 mm2 Red 0.5 - 1.5 mm2 Blue 1.5 - 2.5 mm2 Yellow 2.5 - 6.5 mm2