The catches:
- This is only rated to 3m, and it is more difficult to equalise your ears with a full face mask than a half mask
- The link is to mask only - so the cost is around $500 with the cylinder
- its not great to be playing with filling compressed air cylinders without knowing what you're doing. any contaminants that enter the cylinder that may be benign at ambient pressure can be fatal at depth as the partial pressure increases (eg carbon monoxide, carbon dioxide).
- You won't get the claimed 10 minutes out of it breathing underwater. It is a 3 cubic foot cylinder the same as a Spare Air, which they claim gives you 57 breaths at surface = embolism => death.
underwater.com.au/shop/submersible-systems-spare-air-pack.htmlif you do want to go down this path don't buy this, buy a cheaper spare air unit with a yoke adapter and get your local dive store to fill it - the cylinder will be hydrotested to australian standards and you will have clean air. But you will need to have a diving certification to get an air fill.
In short, if you want to breathe compressed air, do a dive course and then you'll appreciate that this is a waste of time and you might as well either just go diving or just go freediving. If you are a vaguely competent freediver you can easily outlast one of these units on one dive, and you don't have to go back to shore and spend half an hour refilling or pay a few bucks to fill it - take a few deep breaths and do it again!
Background - diving instructor, submarine escape instructor and commercial diver.