26-24 gauge nylon-insulated ring terminals, #4 stud. The nylon insulation provides relief from vibration that can cause the wire to fail prematurely. The nylon insulation also prevents incidental metal to metal contact that can cause shorts. Requires two crimps (terminal to wire strands, terminal to insulation of wire). Standard tools perform both crimps. For heavier usage, use a tool that performs both crimps at the same time.