These are the greatest thing since sliced bread. They are pipefitting cards that contain everything the bluebook does plus some they are waterproof or sweatproof however you want to look at it. They have info about the valves we work with, nut and bolt sizes just so much info im very impressed.  Formulas every fitter needs to know i mean everything very field oriented. They make a pup into a pro in minutes and today i dont know where i would be without them. Im a welder and even my dumb self can figure it out lmao.  very well worth the thiry bucks i paid for mine and any real pipefitter welder ought to have themselves a set. Just info anyone ought to Know.