I've used it from two sources. I don't know if I'm supposed to list them. Both seemed legit. I ran it for slightly less than a month each time, at slightly less than 40mg/day(36mg with one and 37.5mg with the other. Weird dosing I know.), with only about 10 days off in between "cycles". I didn't want to split it up like that, but you know, sometimes things fall through. I think the results of one, two month cycle, without the break, would have been even better. It is very strong, with noticeable increases in strength and hardness within a few days. Both times, over the course of about a month, I steadily gained a little muscle, and lost a little fat, with a slight overall weight gain. Calories were at a slight surplus, obviously. It worked well both times, and the strength and body comp changes were consistent the whole cycles. I didn't use it with test, but I did take 100mg a day of DHEA figuring that my body would have something to convert to estrogen so I wouldn't have joint or libido problems, and I didn't have either. I've never taken winstrol over 40mg/day orally, and it's stronger than that. I thought S4 was pretty good, but S23 is much stronger and better, and I don't think I would really compare them. I didn't notice any side effects, but I haven't had blood tests while on it or right after, so liver, blood cell, and lipid changes may have occured. I like it a lot, and think it's by far the best sarm, but the lack of information or human testing is concerning.