They are 2 piece (commuter series) and the phone slides open. It makes the physical keyboard difficult to use on the top line. I bought one, put it on, stuck it in my pocket and really kinda hated how big it made the phone seem, I will keep it for times when I may need the protection but I don't want to have to pull off the back everytime I dock. It IS the best case out there in my opinion. The button covers work great and the inserts to cover the headphone and power jack can't but help keep the dust and gunk out. In the end, the phone is pretty sturdy and I really dont care if I get a few nicks or dings...character I think it is called. Anyway good choice of covers.