The Apeks DS4 XTX40 regulator is the standard when it comes to robustness and reliability in a UK regulator. The DS4 first stage is the twinset set regulator of choice but provides excellent hose routing on single cylinders and stage bottles. The DS4 first stage is compact but delivers large volumes of gas when you need it most.
The XTX40 second stage is a lightweight and compact, making the regulator comfortable in use whilst also being an excellent breathe. As a member of the XTX family the XTX40 has user interchangeable exhaust tee's, reversible venturi control and the ability to have the hose coming from the right or left hand side of the regulator.
The XTX40 DS4 regulator is perfect for twinsets and recreational divers not looking for a swivel on the first stage. The lightweight second stage makes excellent primaries and backups whilst the ports of the DS4 are positioned perfectly to allow comfortable, efficient hose routing.
Technical drawings of the reversible XTX design can be found here.