Don't know who told you a Ball can eat a large rat, but thats very false info. I really hope you don't plan on feeding live. If he/she is almost 700 grams or "was" then a small rat will do fine. Large rats can inflict some serious damage to a snake of that size, or to any size ball for that matter. I don't feed my 4000 gram female anything bigger then a small when its live. I'll give her a medium f/t from time to time but thats it. Careful where you get your information from, and always refer to this site for good advice not petco lol. Good luck!!