4 Gauge heavy duty PVC insulated ring terminals. Vinyl (PVC) insulation has a flared entry making wire insertion easier. Insulation is molded over a heavy duty tin plated copper 4 awg ring terminal. Temperature rating of 221°F (105°C). Voltage rating of 600 volts. Available ring sizes are: 1/4'', 5/16'', 3/8'', and 1/2''.