The DS4 First stage.
The performance of the DS4 first stage is the same as the TX-40 and 50 first stage (DST first stage )but has no swivel turret for the LP ports

The ATX40 second stage and octopus is smaller and 25% lighter than its TX predecessor. This results in less jaw fatigue and less drag.
This pneumatically balanced is ideally suited for an over-balanced Apeks first stage.
The diver has full control of the venturi by means of a lever so as to prevent accidental freeflow when the octopus is not being used.
The excellent coldwater performance of this octopus is due to the highly efficient heat exchanger on the second stage.

No swivel turret
4 medium pressure ports, 4 x 3/8´ UNF
1 high pressure ports, 1 x 7/16´ UNF