C.O. vs. Hydra

Is the Cigar Oasis a sealed unit? What I mean is...I own a Hydra from Heartfelt Industries, and I really like it, except for one thing. It is refillable (which is great) but that means it is not a sealed unit...so the humidity from the foam in the bottom cartridge will actually hydrate the humidor. In other words, its great for when I open my humi, because it is rehydrated very quickly, or if I want to hydrate above 67%, otherwise with the unit off, it stays around 67%-69%. I like lower percentages on my humidity, so I changed over to the beads from Heartfelt. Now I can get to stay around 64%-66%. This is my question.....

If I had a Cigar Oasis, could i keep a humi at 55% (just an example) because the water is sealed off from the humi? Is it a sealed unit?

I'm a bit confused....on the cigar oasis website they use the word sealed over and over again to describe the water cartridges. The Cigar Oasis XL Plus uses foam in the cartridge like the Hydra does....but they still use the word sealed.... :?