Feeder size?

[Twas-a-Tori]

So I've got my new snake and the lady who had her before me was giving her pinkies but she looks like she could eat a fuzzy(?) Then again I'm basing this off photos I've seen of feeders and not actual experience. All of the dealers online tell you the average weight and length of the mice you are buying but don't saying anything about width and everything I found online about feeder size has to do with width. I really don't want to accidently get the wrong sized mice for my snake. I have a picture of her next to a penny and I'd really appreciate some help. Thanks.