The ST1 is a Balanced Flow-Thru Piston Design using Atomics Jet Seat High-Flow Stainless Steel Piston. Exclusive High-Pressure Piston Seal System is Self-Lubricating for Low Friction and Low Maintenance. The Atomic Jet Seat System has No Sharp Edges that can damage the seat over time, like most competitors' first stages. Instead, Atomic employs a Conical Seat and Blunt-End Piston. Atomics' Valve Seats are Precision Machined from an Extremely Strong Aerospace Specification Seat Material. This design combination is the most Reliable Seat System in the industry and enables the seat to go 2-years or 300 dives without service. Diving Performance is Superior at even Low Tank Pressure. The ST1 is also Freeze Protected with a Factory-Sealed First-Stage that also Prevents Contamination such as Silt and Sand. The Regulator is Nitrox ready for Mixtures Up to 40% out-of-the-box. The First-Stage has 2 High-Pressure (HP) 7/16" and 5 Low-Pressure (LP) 3/8" Ports. The LP Ports are on a Swivel Turret for Ease of Hose Routing. The ST1 Second-Stage is a Balanced Linear Flow Design for Extremely Easy Breathing at all Depths and Dive Conditions. Like the First-Stage the ST1 Second-Stage is Built-to-Last with a Titanium Demand Valve Body, Lever and Sealing Orifice. The Diaphragm is made from High Quality Silicone Rubber. This Pneumatically-Balanced Poppet Second-Stage has Atomics Patented Seat Saving Dynamic Orifice which unlike most Second-Stage Orifices is a Floating Valve Design which Reduces Wear on the Second-Stage Poppet Seat when the Regulator is not pressurized adding Life to this Important Seal.