I'll keep this short and to the point. I had two vials from viper that are clearly underdosed with bloodwork to prove. The vials came clear and over about 2-3 months they turned yellowish color, basically the same as my pharma test. Viper assured me they were fine. Used them and wasn't exactly happy... I was on 600/week and got a result of about 2000, which is my normal 500/week result. Last cycle with viper on 650/week, my level was 3800. I bumped the 600/week to 750/week but started the second yellowish vial. Imagine my surprise when my level came back 1700. I emailed viper two weeks about the issue and never got a response. Never had a problem in the past, but if somehow you get test cyp from batch TC020, I might be wary of using it. I guess I'll find a new source which is unfortunate.