I am getting ready to start shipping this years chicks this fall and looking for shipping containers. I found Horizon offers a lot of different sizes and with so many to choose from I am confused. http://www.hm-e.net/our-boxes.html I was quite pleased to find that the boxes are already postage paid! I am wanting to buy a good amount of the right ones, buying small quantities does not make sense when I have so many birds to sell. So those of you who do shipping, what size do you recommend?