 13 ounces. Some of them aren't grams, but you buy a 12-ounce can of refrigerant, you hook it up. Are you an ounce low or are you two ounces low? Are you half an ounce low or are you five ounces low? And how do you know what you're putting in there unless you've got some kind of scale to weigh it? So the chance of you topping off the refrigerant to the point where it's going to work effectively is almost zero. In most cases, everybody puts the whole can in.