Both OSTA and S4 are ideal for PCT, although they can be administered concomitantly with AAS. It is akin to running IGF-1-LR3 with GHRP-2 for example, as an ancillary method to retain the newly realized muscle mass. There has been some speculation and from what I've heard even blood work, that shows a slight suppressive effect from SARMS SEARCH's products, but it is minimal and reversible.