Ive used it in the bis and tris and got really nice and clean results, I gained overall probably an inch on my arms in about 2-3 weeks, if you dont abuse it and know what your doing its just another tool we have at our disposal. yes it does get painfull injecting all of that solution into the muscle belly, but after a week it hurts so bad you dont feel it anymore....calfs are a great spot for this, although that is the last place I need it, but if you are lacking mass on them make sure to learn where each calf muscle ties in at and make sure to hit it in the center of each belly.