They open at the back and swing toward the front.
$99 GA bag from these guys:
http://www.mutazu.com/ (
http://www.mutazu.com/products.php?cat_id=7&menu=Hard%20Saddlebags&product_id...)
They have others that open on the side, some with lights (dim LED's) etc.
I saw a pic on the forum of another bike with 'em and thought they were the perfect size and I was looking for something lockable. They were certainly cheap enough to take the risk and throw a few extra bucks for reinforcing. I Googled reviews and most guys reinforce with sheet metal. I've redone the mounts; added a thicker bar inside across the top and removed the rubber grommets.
I can fit a fair amount inside; even my armored MC jacket folded up on hot days. All the various gloves needed for riding in Denver, tools, rags, lunch...
Definitely not solid like fiberglass. They are ABS plastic but again, cheap to buy and play with.