This is a White Labs product made with Brewers Clarex. The underlying agent is a proline-specific endo-protease derived from a selected self-cloned strain of Aspergillus niger, which I understand is a fungus. I have used this twice. My beers have been much clearer, but head retention and taste seem to be adversely affected. I was interested in this because of a Zymurgy article suggesting this agent reduced the gluten proteins in beer. I don't know about that, but I'm not sure I like its impact on my beer. Actually, I wonder if I might be having a reaction to this fungi. I am allergic to wheat, but not gluten that I am aware of. Any anecdotes would be appreciated.