My Husband and I recently decided that the kiddos where finally old enough for us to get back into owning snakes and we purchased 2 royals. I and he in the past have owned and dealt with various pythons and boas. Neither of us however have until now used f/t food and what I am finding is that the size variation is slightly different everywhere. So my question is our two girls are 17 and 20 in long and about as big around as a Quarter normally when i lived in a bigger city I would have simply gone down to the local store and picked out an appropriate sized mouse or rat and fed it. When buying f/t what size food would be best for our new girls when buying in a 50 qty bulk our local pet stores carry mice and then x lrg rats so not really a great selection in the f/t department. They are consuming 1 hopper every 4-5 days at present and have thus far declined striking at a second although the next day they are displaying their i'm hungry behavior (running their head up and down the section of the cage that they are fed in ( while their custom cage is being built ) that smells like mouse. I am leery at this stage of moving them up to small rats given the weight of the small rats that they would be to large so should i move to adult mice?

sorry if it seems a bit rambled off i am accustomed to the best answers come from the most informed question.