They are not intended for human use. the only reasonable legal OTC serms would seem to be 6-oxo extreme double dosed, dermacrine sustain or post cycle support (which isn't out yet). There is limited evidence on either of these effectiveness, but they seem to be the most reasonably likely to be effective OTC PCT products.
If you go back in time just a few years, the research chemicals were not so readily available, and cycles of prohormones were run with nothing, or sometimes chrysin or once it came out 6-oxo regular as the only things in PCT. Too risky to be worthwhile in my opinion, but people lived