Objective: The Baska and the Protector Laryngeal masks are single-use second-generation supraglottic airway devices with a dual gastric channel. Material and Methods: 64 American Society of Anesthesiologists physical status 1-2 patients between the ages of 18-70 undergoing retrograde ureteroscopic surgery enrolled in this prospective randomized study. Results: Demographic airway variables and airway characteristics were similar between the groups. Insertion time was shorter in the Baska mask group [14 (11-20) versus 20 (13-27) seconds, p=0.035]. The need for optimization maneuvers during insertion was higher for the Baska mask group (p=0.009). The laryngeal mask airway (LMA) insertion was easier in the LMA Protector group (p=0.023). The first insertion success rate was 75% for the LMA Protector and 84% in the Baska mask. The total success rate of both devices was 91%. Nasogastric tube insertion was faster in the Baska mask group [14 (12-15) versus 17 (13-25) seconds; p=0.003]. Fiberoptic views were similar between the groups. Minute volume after insertion of the device was higher in the LMA Protector group [8 (6.5-10) L/min versus 6 (5-7) L/min; p<0.001]. Expiratory tidal volume was higher in the LMA Protector group after insertion of the device, 15 minutes, 30 minutes, and 45 minutes after insertion (p<0.001, p=0.032, p=0.001, p=0.027 respectively). The end-tidal sevoflurane concentration (ETsevo) 30 minutes after device insertion was higher in the Baska mask group (1.49±0.38 vs 1.75±0.36; p=0.014). Conclusion: The LMA Protector is superior to the Baska mask in providing higher tidal volumes and decreased need for optimization maneuvers in retrograde ureteroscopic surgery.