You should base the feeders you order on what the snake is currently eating. If you buy rats (which is the preferred and better choice to feed with) and the BP is a mouser, you're stuck with a bunch of f/t rats that it won't eat. Also, if you're buying your BP from a breeder, ask them if they know where you can buy your feeders locally. It really cuts down on costs. I bought 10 rats prekilled when I bought my first BP for $4 from the breeder but he lives an hour away from me. I now have a connection closer to home where I can pick up any size rat for $2 each and lower. It's really nice to have that option instead of the expensive pet store.