Gardner Bender 4 AWG 3/8 in. Stud Size Vinyl-Insulated Ring Terminals in Yellow (4-Pack) 15-098 - The Home Depot
Amazon.com: 10pcs 4 Gauge 4 AWG x 3/8” Pure Copper Cable Lug Terminal Ring Connectors with Dual Wall Adhesive Lined Red + Black Heat Shrink Tubing – by WNI : Industrial & Scientific