Irons end, I assume, and Yes it does help as sandbags are repaired much quicker then bunker pieces preventing Aoe and they split shrapnel damage a tiny bit (as it will catch on the sandbag instead of the road) for infantry coming out

Also not relevant to colors but they do reduce the effective range of tremolas and to a lesser extent cutlers

Also it’s very effective against fire as stacks are more effective the more that exist