Hope this helps.
The two most commonly used units of weight (or mass) measurement for cooking in the U.S. are the ounce and the pound. Do not confuse the ounce of weight with the fluid ounce, because they are not the same; there is no standard conversion between weight and volume unless you know the density of the ingredient.
But in your case you're taking the same measurement for both. A gallon of plastic or 128 oz and a bait using 5 oz. Weight has nothing to do with it.