The back of the case has "ribs" sewn in for extra strength and support, and the lumbar strap at the waist is attached by velcro and can be easily adjusted. It opens in half like a suitcase, and it has several pockets that open on the outside as well as inside. There is even a removable wetsuit / wet gear bag inside.
I am able to fit everything I need for a triathlon in this bag and still have room to spare. On the right, you can see one shot of the bag without anything in it.
Below is all the stuff I need for a race that can easily fit into the bag. Fully packed with this gear, the bag weighs about 14 lbs. There is still room to tuck in additional items such as extra clothing.
See below each picture for comments. You can click each picture for a larger view.
The wetsuit slides into this removable water proof zippered bag. Here's my wetsuit partway in. I usually throw my goggles on top of the bag, once it's zipped up.
The wetsuit section is under the silver on the right. You can see three zippered net pouches on the two sides. I keep a variety of items in these and as you can see, there is room for more.
The left side has an upper and lower zippered section handy for keeping shoes and clothing. I'm not too big so I can fit both running and biking shoes in there.
In the upper section, I have my towel and my tri top, socks, and shorts. I could easily fit more clothing in here such as extra socks, a jersey and a vest
Once the bag is zipped closed, there is access to the other compartments - this form-fitting section holds my bike helmet (and anything that might fit inside the helmet.) The top section has a space for ID, papers, wallet or ? and has a built in "gear" list printed right on the flap.
In addition to a zipper, there are straps that click shut and hold the two halves together, and you can always hang stuff from these straps as well. A water bottle holder is on one side, and a small flat pocket for papers etc is on the other side. There is a pouch on the waist band and an ipod earbud cord hole in the top the bag.
Overall, I think think this is really good bang for your buck if you are looking for a well-made, roomy, versatile travel bag.