If you’re looking for a hard case to protect the rear of your iPad 2 I can highly recommend the Belkin Snap Shield.
It’s a snug fitting hard case made out of a soft touch plastic which clips around the edges of the iPad, providing plenty of protection to the rear of the iPad without getting in the way of using it. It’s also designed to work seamlessly with the Apple Smart Cover and comes in several different semi-translucent colours.
Highly recommended.