Prime Primo 100 seems to be legit. At least my E2 has more than halved.
Not the best way to determine if it's legit or not. E2 reduction could be from EQ or even worse a liquid aromasin for example. Checking your free test and the SHBG before and after it's a more legit way to pinpoint if it's primo or not. Just to have it in mind if you want to "test" primo in the future.