No this isn't a batman backpack, it's actually been made with baseball players in mind. It just so happens that the Mizuno G4 Backpack really suits volleyball players as well.

FEATURES
J Hook Clip: Hang your bag up on random stuff at home or in the stadium.
Felted valuables pocket: Keep phones or any other valuables safe while your having a hit.
Easy access pouch: Great for your shoes or those smelly knee pads, uniform or towel.
Bat sleeves: Easily holds two baseball bats on each side. If you don't usually carry baseball bats to volleyball, just use them as water bottle pouch.
Dimensions: (H)20" x (W)14" x (D)9"