For a pad this light, 4 inches of thickness is as cushy as it gets. The weight savings are due to the pad’s shape, which is optimized for the female body: The Etherlight XT starts narrower (about 20 inches) at the shoulders and transitions to 21.5 inches wide through the hips and knees. And it’s 66 inches long, rather than the standard 72. (There’s also a unisex version.)
Metallic, heat-reflecting particles are laminated to the synthetic fill, which bumps the R-value to 4.2, compared to 3.8 for the unisex version. Our tester snoozed comfortably on 20°F nights in Olympic National Park.
The Etherlight XT packs down to slightly larger than a 1-liter Nalgene (and slightly larger than the NEMO Tensor Alpine).
We were able to fill the pad in three or four pumps with the stuffsack that doubles as an inflation bag.