They have a few different versions now, but the key to the membrane is that it’s really thin. It’s not like most average Joes can make their own even if they buy a bunch of PTFE pellets. It’s also overkill for most people and daily life, but Gore Tex (or some of the newer competitors) is worth it when backpacking or biking; you don’t want to carry the weight of a waxed canvas jacket for a long trip.