The Ball Drop Frac Sleeve is utilized in multi-stage reservoir stimulation. An actuating ball is dropped from surface to the corresponding ball seat down hole. The ball and ball seat sizes are stepped up from smallest to largest (toe to heal). Once a ball is dropped and pumped down onto a seat, hydraulic differential pressure causes the inner sleeve to shift down opening the sleeve. The opening of the sleeve provides communication with the reservoir allowing the stimulation to begin. This process is repeated until every sleeve is opened and the hydraulic fracturing process is complete.