Vinny, Google "bar's radiator stop leak" and get to the Bar's home page, then download the PDF product page. The tablets and powder are listed, along with a slew of other products. The page also lets you download the product tech sheet for each item.
I would stick with the B12P (?) powder or HBC tablets, the GM recommended cooling system supplements. 3 tablets/equivalent crumbled in the lower hose at refill.