Canon Power Booster PB-E2 for EOS 1V/3/1N/1

The PB-E2 is a rugged piece of machinery that will dramatically increase your EOS's shooting speed--up to 10 frames per second in most cases! The controls near the bottom of the grip make vertical shooting just as easy as horizontal. These controls include the shutter, main control dial, AE lock, and focusing point selector."