Is the DGX Gears FIRST regulator suitable for sport SCUBA applications?

The short answer is "yes". The FIRST regulator is a classic downstream balanced piston design 1st stage that is popular for reliability and minimal maintenance in dive shop rental fleets. This inexpensive first stage provides good performance for its design class and we have no concerns using the FIRST regulator for recreational sport SCUBA diving depth applications. However, we do not recommend the FIRST for breathing use in extended range depths or in very cold waters.