Stronger Spring for Apeks DS4

This spring is stronger than the stock DS4 spring to allow first stage intermediate pressures from 14 bar (200 psi) to 20 bar (290 psi).  This allows divers to run a higher intermediate pressure for increased max depth on an mCCR.

Note: always subtract 2 ATMs from max depth calculations.

Example: (210 psi / (14.7 psi/ATM) – 2 ATM) x (33 fsw/ATM) = 405 fsw