The E2 is a hand strap, not a wrist strap. If you're looking for a wrist strap, where the camera dangles free from a loop around your wrist, Op-Tech makes one.
A hand strap wraps around the back of your hand for some extra support while shooting, and also makes it more secure to hold/carry the camera one-handed. With the battery grip, you don't need the tripod socket attachment that comes with the E2, since the battery grip provides the lower lug for the strap.