HFV Car audio 4 awg crimp ring terminals for power ground wire- cables. 4 pack
 
Solid copper with tin plating for maximum conductivity. Come with silicone sleeves as shown.
Choose 3/8" hole or 5/16" hole size for bolts.
 
You will need a crimp tool to install these.
Here is a cheap hammer type you can buy Here: https://amzn.to/4neAG7x
Or this is a better hyhdraulic one here: https://amzn.to/45PL2VE