For this purpose any scale that weighs from a few grams to 5000 will be fine. It doesn't need to be accurate just able to repeat the same object at the same weight. It is the relation of snake to food that matters. Unless you are selling them there is no need for high accuracy. I find I get feeders and have a variation in sizes so ordering the correct size I usually get some a bit small and some a bit big. I often break the package down to individual animal (or pairs one for each of yours) wright the weight on the out side and return them to the freezer. I'll start with the smaller ones and work to the larger ones. If they are all manageable I mix it up a smaller one one week the larger the next, rather than feed all the biggest ones and then be light for a while.