It is the same as most other piston regulators. The ambient chamber is filled with christolube and the rubber trim ring is one that doesn't have holes. It can be done on the B1, T1, Z1 as well, and I believe it will be exactly the same as the M1, even down to the part used. (The trim ring.)
Christolube is highly resistant to oxidation, hence the 80% O2, and I think also less viscous than silicone grease, making the impact on performance minimal. It's also pretty expensive, so servicing will cost more if you have an environmentally sealed regulator. (Not sure, but maybe $20 more for the christolube?)
I'm looking into getting an M1, but if I do, I'll probably get rid of the environmental sealing on the first service, as I don't really need it, it may potentially be messy, and I would have to pay for the christolube every time it is serviced.
I see you are in the Philippines, why do you need environmental sealing?