It's a dense piece of writing. They claim chemical adsorbtion but declare they don't use "GAC [granular activated carbon], carbon block, extruded carbon and other coarser charcoal filters."

My takeaway is they're using some form of carbon, but one that doesn't fall under one of those categories. Carbon adsorption is a very common form of chemical removal technology and since they cite TCE and other organic contaminants, almost assuredly at use here. (It's how they removed semi-volatiles when I worked in environmental remediation.)

Can somebody cut one apart and report back?

The rub is carbon only removes certain classes of chemicals and even the treatable chemicals have varying affinities for carbon. The poor consumer has no hope of knowing 1. what's present in the source water 2. whether the filter is removing it and 3. at what point the carbon becomes saturated and begins desorbing the very chemical it was previously removing.

First Need was the first filter I bought. I moved on when lighter, faster ones became available. But I don't filter for anything more complicated than microorganisms so haven't concerned myself with chemical removal. If I hiked where there was agricultural or mining contamination I'd probably re-think the whole bring-in-your-water thing.

Cheers,