Patients who consented to PNL for management of their renal stone would be approached about entry into the study by either of the primary surgeons, the research coordinator, or the research fellows. Patients would understand that PNL is not an experimental procedure and that the research project specifically is comparing the two lithotripsy devices with similar mechanism of action and safety profile. The goal in all cases would be to render the patient stone free. The patients care would not deviate from our standard PNL care protocol, summarized below, with the exception of the use of a different lithoclast.