I was checking out these packs too. On the Flightmax 30c. The dimensions are all different on some of the packs. The 4s is 140x48x33mm and the 3s is 143x50x24mm.
I wanted to put the 4s in a rustler. I wonder if it would fit?

http://www.hobbycity.com/hobbycity/s...idproduct=8588
http://www.hobbycity.com/hobbycity/s...idproduct=8587