This is my second bottle of Dave's Original Insanity Sauce, and the first one lasted forever.  I have tried several "red hot" sauces from the supermarket, and nothing is in the same ballpark as Dave's.  One drop in a pot of spaghetti sauce makes it nice and spicy.  As others have warned, wash your hands after handling the bottle and before touching your eyes.  The key words here are "use sparingly."