I just know the one I was buying was in a green can by Great Lakes, I didn’t see different ones to choose from. I haven’t been using that lately as it’s way more expensive than the Organica brand I get from Costco Canada.

He talks about ascorbic acid and I don’t agree with him on that, because Vitamin C is not a complex, ask any orthomolecular doctor that.

My favorite brand of collagen in Great Lakes in the green can. I haven’t been using it these days, In Canada and buying Organika (Canadian brand) at Costco.
But I think vitamin C and copper are more important, other minerals too – our bodies need to make our own collagen. With copper you should be taking zinc as well.
Collagen is everywhere in your body, eyes, bones, ligaments, bones, muscles etc.
Dr. Eric Berg says copper is the #1 nutrient that raises collagen.
Diatomaceous earth would be helpful too IMO.
Check out this video by Dr. Berg:
https://www.drberg.com/blog/the-1-nutrient-to-boost-your-collagen-not-vitamin-c