This is the backing ring that holds the outer part of the boot onto the knuckle, this part will come as a used surplus piece, bolt kit is available as an option.
Boot Rings are sold individually Bolt kits come as a pack of 12 and are enough to do 1 Boot
This is the ultimate upgrade for dealing with the pesky 5 ton boots. This makes installing the boots significantly easier than the using the typical factory screws. Also by incorporating a lock nut there's no need to run tie wire and this will also allow the clamps to stay snug without over or under-tighting the clamp!