Bala

is an Arrancar technique that hardens the user's reiatsu, and releases it from their hand like a powerful bullet. It's not as powerful as Cero, but it's about 20 times faster. Its power also varies with the Arrancar and Espada. Some prominent users are Yammy, Wonderweiss Margera and even Ulquiorra Cifer. The more powerful the Arrancar, the more enhanced Bala becomes.