JST Insulated Crimp Ring Terminals. The JST R-Type Ring Terminal is made of oxygen free cooper and features excellent electrical characteristics. The Nylon insulation ensures high flame resistance and insulation properties. Features ; Benefits. Flared entry. Oxygen free cooper with excellent electrical characteristics. High-strength brazing. Insulation. High temperature resistance (up to 105oC). A range of insulated crimp ring terminals for use with a variety of wire and stud sizes. Insulated crimp ring terminals with part numbers prefixed ' FVWS ' have flared vinyl insulation and a butted seam Insulated crimp ring terminals with part numbers prefixed ' FVDWS ' have vinyl insulation, copper sleeve and butted seam Insulated crimp ring terminals with part numbers prefixed ' N ' have straight nylon insulation Insulated crimp ring terminals with part numbers prefixed ' FN ' have flared nylon insulation