The Legend regulator series incorporates a proprietary over-balanced diaphragm first stage design coupled with a high performance balanced second stage. The over-balanced first stage achieves unprecedented performance by increasing your air supply the deeper you go. The balanced adjustable second stage reduces breathing resistance to near zero with a lightweight balanced valve seat designed to respond instantaneously to the slightest inhalation. The Legend regulator series is the best performing regulator Aqua Lung has ever offered. Legendary performance from Aqua Lung: a tradition for 60 years.