If you're shelling out for primo, hopefully it's not just for AI.
Primo would be the least convenient and most expensive AI.
There are people who view anastrozole as a toxic compound and prefer to go another route. These people seem to gravitate towards primo for this purpose. They probably believe that it has more muscle building properties than I have personally experienced whether I'm right or wrong. In reality, it's not that expensive to use a few hundred mgs of primo if you have any sort of means.