Sleeve gastrectomy is now the most commonly performed bariatric surgery. While many studies have evaluated factors that may minimize post-operative hemorrhage and staple-line leak, the investigators are unaware of any studies that compare outcomes between devices from the two main stapler manufacturers used in this surgery, Covidien and Ethicon. The purpose of this study is to compare intraoperative characteristics, such as time to create sleeve, intraoperative bleeding, and time needed to load each cartridge, and post-operative characteristics, such as any complication requiring readmission (leak or hemorrhage), further surgical intervention, and weight loss, between patients who underwent sleeve gastrectomy with Covidien devices and Ethicon devices. Currently the investigators predominantly use whatever device is cheaper, but cost should not be the primary decisive factor if one device is superior to the other. If one device has better clinical outcomes, it should be the preferred device regardless of cost. If neither proves superiority, the investigators can justify using cost to determine which device to use in patient care.