This is the Dive Rite XT1 1st stage with XT4 2nd stage regulator Features: XT1 First Stage Material: Black DLC-coated brass. Weight (DIN): 1 lb, 15.2 oz (885 g). Weight (Yoke): 2 lbs, 6.8 oz (1,100 g). Intermediate Pressure: 140 PSI. 5 LP ports (3-8/24 UN). 2 HP ports each angled 90Adeg from fitting (7/16-20 UNF/ISO 263). The XT1 First Stage is environmentally sealed to protect against internal corrosion, contaminants, and freezing so you can feel confident diving this regulator in any underwater environment. The XT1 is suitable for oxygen-enriched mixtures if precautions are taken (diver must use oxygen-compatible materials, keep the regulator clean from contaminants during assembly and use, and open the tank valve slowly). XT4 Second Stage Weight: 9.4 oz (266 g). Balanced downstream internal second stage valve. Second stage adjustment knob fine-tunes inhalation effort. Can be oriented for left or right hose routing. Oxygen compatible O-rings and lubricant. This regulator was designed using the Venturi Effect to direct airflow directly from the valve to the mouthpiece, resulting in the smoothest possible inhalation. An "easy grip" dive/pre-dive switch allows the diver to avoid a free flow at the surface and works well even with gloves. This adjustable design enables the diver to fine-tune their cracking pressure to suit their preferred breathing resistance.All internal moving parts in the XT4 Second Stage are coated in Teflon and a finned metal heat exchanger is utilized for improved cold-water use. The XT4 is suitable for oxygen-enriched mixtures if precautions are taken (diver must use oxygen-compatible materials, keep the regulator clean from contaminants during assembly and use, and open the tank valve slowly). Cutting-edge combination of Dive Rite&&';;s XT4 Second Stage and XT1 First Stage Regulators. A solid first and second stage regulator is the foundation for any regulator package you use while breathing underwater. Customize this kit with any other Dive Rite regulator components to suit your diving needs. This base regulator set provides seamless, controlled breathing for the most comfortable dive possible. "