Love detachable interior strap and can adjust to stay open for singing or lay flat in your lap;ample pockets inside both covers; like the clear plastic window slot for my business card or other identifier; held a over a dozen sheet music booklets - maybe more or less depending on your music; finally, the exterior strap for your hand is very sturdy (so many other books have a clear plastic strap and perhaps they are sturdy as well, but I figured this had better odds)