Nilight 150PCS Copper Wire Lugs and Heat Shrink Tubing 2 4 6 8 10 AWG Heavy Duty Battery Terminal Crimp Connectors 70 PCS Copper Lugs 80 PCS 3:1 Heatshrink Tubing Assortment Kit, 2 Years Warranty. Each bare copper lugs are engraved with wire gauges and stud sizes. And the 3:1 shrink tube is color coded with black and red, easy to identify the polarity of the wires.