I can only guess that this grip is designed for those whose palms get all sweaty when playing the DSi. And you wouldn’t want to drop your expensive portable, now would you? Well, the Cyber DSi Game Grip will keep it firmly in hands.
It even provides enough space to store another game cartridge on the back with an SD memory card. It’s currently available in Japan, but if you have a severe case of sweaty palm you could always import one.