Specifications

Test Stats

The Delta 4.2 combines a FDX-10 first stage and a Delta second stage. This is basically the same reg as the Delta 4.1 we tested last year, only this version has a redesigned second-stage swivel. The Neo is the same lightweight second stage we saw last year, but this year it too is teamed with Oceanic’s flagship FDX-10 first stage. The Neo is pneumatically balanced and fitted with an Adjustable Venturi Switch for simple dive/predive adjustment. The Delta features Dynamic Adjustment, a mechanical balancing system that uses an adjustment knob. By turning the knob, you find the inhalation effort that suits your diving style, then Dynamic Adjustment takes over, automatically adjusting itself to maintain the same inhalation effort regardless of depth. The FDX-10 comes with an environmental kit and Oceanic’s exclusive DVT (dry valve technology). This is a valve that fits in the high-pressure inlet at the yoke to keep moisture and contaminants from seeping into the first-stage orifice in the event the dust cap is accidentally left off.

Performance:

The Delta 4.2 couldn’t quite match the performance of its predecessor at the breathing machine test level that most closely represents recreational diving — apparently due to the second-stage swivel — but breathing performance was nonetheless above-average across the board. On the other hand, this year’s Neo enjoyed a huge uptick in overall performance now that it’s teamed with the FDX-10. On the breathing simulator, the Neo earned excellent scores in three of the four test levels, including some of the most extreme test levels. In real-world tests, both regs performed nearly identical. Test divers rated them easy, dry breathers in all diving positions. They were also easy to clear due to pliable yet powerful purges. The Delta’s breathing-resistance knob was one of the few designs we tested able to make a noticeable difference in inhalation effort. The Neo’s venturi switch was a favorite as well. It is large and easy to access when wearing thick gloves, and has a nice ratcheting action to it. Both regs come with comfortable orthodontic mouthpieces with high-density bite tabs.

Bottom Line:

The Delta 4.2 is a solid midrange reg, delivering very good performance and offering some nice design features. The second-stage swivel is a nice add-on, increasing range of motion. When it was hooked to a CDX-5 first stage, the Neo was a solid performer; hooked to an FDX-10, it’s an exceptional performer.