West Texas livestock grower has great review of salt blocks, 2020 I think. Google colored salt blocks
Ya there's a green one too,sellium or whatever it's called.
I've also seen that one out in the woods as well.
I'm just going with trace mineral,and not all those color blocks.
I can say without a doubt,I had just regular red trace mineral salt in the same areas as I seen the color blocks.
Looked like deer and Elk was still hitting mine pretty hard.
I don't think it makes a huge difference.