This is a Metra sku: SB0 hard plastic Snap Bushing Grommet for my 2/0g wire. I have verified that this works perfectly on the EB Flex brand wire I sell. 

These grommets are very basic to install and help to protect the wire as it goes through holes in your firewall. A must have when installing any power wires through your firewall. These keep the wire from being sliced and shorting out.

Inner Diameter: 0.69"

This grommet DOES work on car audio 2/0 cable. 
This grommet DOES work on EB Flex 2/0 welding cable.
This grommet DOES NOT fit my #FAM 1/0 cable (grommet is too small)