Sea to Summit Ether Light XT Insulated mattress

The Sea to Summit Ether Light XT Insulated mattress, with a 4″ thickness and advertised R-value of 3.8, seems like it should make for comfortable sleeping in all but the coldest weather.  My size Regular is about 71″ long and tapers from 21″ to 15″.  The actual weight is 472g (16.5 oz) instead of the advertised 15oz.  In addition the stuff/pump sack adds 55g for a trail weight of about 19oz.  In comparison, my Exped Downmat Winterlite is 7g heavier, 1/2″ thinner, double the R-value, and only a bit more expensive.

The flat valve-within-a-valve works well.  Open the outer valve and the mattress deflates in a couple seconds.  Use the inner valve to inflate, or press the small “button” inside to let out a little air to fine-tune the pressure.

The Airstream combination stuff sack/pump bag seems to work well and uses the same size attachment as the Exped Schnozzle so you can use either.  The Schnozzle is larger and can inflate the mattress with about 1.5 “pumps”, whereas the Airstream needs about 3.  Inflation time is about the same either way and their weight is the same.  The Schnozzle has a much larger opening and can be inflated by shaking it a bit instead of blowing into it so that can help keep a bit of moisture out of the mattress.

Also included in the package is a repair kit (patches and replacement check valve) and fasteners for the Pillow Lock feature.  I don’t have one of their pillows so I can’t comment on that feature.  The mattress uses a different insulating material, and seems less “crinkly” than the ThermARest Neo Air.

I got this too late for the Arkansas backpacking season and haven’t slept on it yet so I’ll post updates once I have some time on it.

June 3 2019


July 2019 update:  I spent a couple nights on the mattress in Wyoming’s Platte River Wilderness and have no complaints.  It is quieter than a NeoAir but still makes some noise.  The extra thickness does provide more comfort for me, as a side-sleeper.


The product was purchased with my own money.  I have no material connection with any companies, products or services mentioned in this post.