Quote Originally Posted by Just Jeff View Post
The only place I've ever seen anyone claim that the Clark is 20F hammock by itself is on the Clark website. I've never heard anyone claim personal experience a Clark near that temp without additional insulation.

YMMV, of course...but there are a lot of Clark users here, and winter hammockers here, and I have a strong feeling that if that claim could be validated we'd have independent evidence of it by now.

Or maybe I just haven't been keeping up...if I'm mistaken, someone please point me in the right direction.
There are two reference to the pockets that I can find on the site and you have it slightly off

"Quote from Clark site"
Patented pockets for insulation (Four-season models):
The Clark North American is the only hammock that removes any need for insulating pads in most weather. The insulating pockets provide a stable air mass underneath you to block cold air from reaching your back.
"Quote from Clark site"
The Z-Liner system fits four-season models to create a comfortable bed in temperatures below 32° F (0° C).

and

Cold Weather Ratings for the Z-Liner are difficult to specify since they depend greatly upon what kind of sleeping bag or quilt you are using inside the hammock and how whether you are a cold sleeper.
In general, the additon of the Z-liner should allow you to comfortably sleep at least 20° F (9° C) lower than you otherwise could. The Z-Liner has been thoroughly tested to work extremely well down to at least single digit temperatures (Fahrenheit) when deployed correctly.
I hope that helps