Nutrobal is an HGH analogue. It signals the pituitary gland to increase HGH output in the body. I would say it's equivalent to about 3-4iu of pharmacy grade HGH per day.
Surprisingly, it should not lead to lower back pumps. If you are getting those, then your product is laced with either oral steroids or prohormones. In any case, its a red flag for a fake product.