feeder rats & mice

we supply feeders, we arn't that well known, as most of ours go to reg. buyers, when we get a new buyer they
often have aproblem with mice & rat sizes, why do we have to have so many sizes, & should there be a wgt standard . i check most all rodent adv. i see, recently i saw an ad with 9 different sizes of mice, is this many sizes needed, i took on a new custermor, in NY with a large # of BP
shipped him alarge order of small rats what he had ben buying elsewhere, the shipping was over 100.00 , he recived the rats & told me to shipp mice, the BP could not eat my sall rats for at least 6 more months. do we need to set some stndards on rat  & mice sizes,if so some of you feeder dealers, lets get it started, i would hate to but 400.00 & 100.00 shipping for feeders i cant use for 6 -8 months
C.G.Arnold       WDC!

RATS                            MICE
med 70 gr                     weanling 14 gr
sm 45 gr                       hoppers 8 gr  
weanling 30 gr               fuzzies 5 gr  
pups 20 gr                    pinkies 1.5-3 gr
fuzzies 14 gr  
pinkies 8 gr

I do all my sizes by weight. As for 9 differnt sizes for mice wow. Unless they're charging for every gram I wouldn't be able to figure out how to get 9 sizes.(lol)
Any how I do weights so that way people have some idea of the size they will be recieving. Other then that I have no idea, because there isn't much consistency out there. I try to be about the same as the average. I don't think this helps but this is what I do.