Nemo Tensor Extreme Conditions Mummy Sleeping Mat | Tested and reviewed

Getting a warm and comfortable night’s sleep can make or break the camping experience. Can the Nemo Tensor Extreme Conditions sleeping mat guarantee just that?

from Nemo
RRP  £250.00
Man inflating Nemo Tensor Extreme Sleeping Mat with snowy mountain backdrop

by Ben Weeks |
Updated on

You might not have heard of Nemo before. No, not the lost fish. No, not Jules Verne’s submarine captain. We’re talking about the American camping kit brand. It’s certainly not unheard of in the UK, with many well respected independent outdoor gear stores stocking Nemo’s excellent tents, sleeping bags, and other camping gear like this Nemo Tensor Extreme Sleeping Mat. But it’s not as widely available or well known as certain other brands. And, as those who use its products will be keen to tell you, Nemo kit is worth hunting out – it’s good stuff.

How good? Well, if this Tensor Extreme Conditions (or Tensor EC for short) sleeping mat is anything to go by, very good. You see, outdoor gear is often about compromise. In the case of sleeping mats, if you want a product that’s very light and very comfy, it’s probably not going to be very warm. Or if warmth and cushioning are more important, you’re likely to have to accept a heavier weight. Or if you want warm and light… you get the picture. But the stats attached to Nemo’s Tensor EC seem to fly in the face of that philosophy. This sleeping mat offers an incredible level of insulation, a sumptuous depth of cushioning, and yet still sits on the lighter side of the scales. Surely, there must be a catch?


  • Warmly insulated
  • Deep and cusioned
  • Surprisingly lightweight


  • Quite pricey

Possibly. The Tensor EC is not a cheap mat. If your previous sleeping pad purchases have been of the old-fashioned closed-cell foam camping mat variety, you might just choke on your dehydrated pasta meal at the price of the Nemo. Even compared to more modern inflatable and self-inflating designs it’s pricey. But those stats are impressive, and if you look at alternatives from other sleeping mat brands that are even close to the performance of the Nemo, well, their prices aren’t that different.

So, we can probably agree that this isn’t a mat for everyone. But here’s the thing: it’s not meant to be. This is a mat for serious campers, for those that will camp out in almost any weather at any time of year. And if you count yourself among that group of hardy adventurers, the Nemo Tensor Extreme Conditions sleeping mat may be worth a closer look…

Remarkable warmth

The headline statistic of the Tensor Extreme Conditions is that 8.5 R-value, making it one of the warmest backpacking mats money can buy. This incredible warmth retention is attained using four layers of floating Thermal Mirror metallised film, strategically suspended within Nemo’s Apex baffle design. And because Nemo use (and was in fact involved in establishing) the ASTM F3340 universal standard for R-value testing, you can be sure it’s a genuine and comparable value.

Deep cushioning

Backpacking sleeping mats used to be necessarily thin; it was the only way to make them packable. Technology has moved on and we can expect more comfort from our mats, but the 9cm (3.5in) of stable cushioning provided by the Tensor EC is still a luxurious treat which makes for a deliciously comfortable night.

Surprisingly lightweight

Warmth and comfort are relatively easy to achieve if there’s no weight restriction, but to cram an R-value of 8.5 and 9cm of cushioning into a mat weighing less than half a kilogram is astounding. The weight is kept low because of the use of the Thermal Mirror film, which retains high levels of heat while weighing next to nothing.

Easy up, easy down

Along with a drawstring stuffsack and a repair kit, the Tensor EC is supplied with a Vortex pump sack. This clever but simple device can be used to inflate the mat in a matter of minutes – and without introducing moisture into the pad from your breath. In our inflation test it took fewer than four inflations of the pump sack to fully inflate the Tensor EC with minimum effort. Nemo’s Laylow valve makes deflating the mat even faster and has been updated for the Tensor EC to improve ease of use.

Tough but gentle materials

The underside of the Tensor EC is made from puncture-resistance 40D nylon to protect the mat on tougher terrain. The mat’s upper is made from premium 20D nylon to provide a soft, and comfortable sleep surface. The construction of the mat is also impressively quiet, so you won’t keep yourself or your tent-mate awake if you shuffle around in the night.


Such warmth and cushioning at this weight borders on the miraculous. Certainly, there’s a high price attached to such technology, but for 4-season campers who will still be sleeping out when the temperature drops, in our opinion it’s a price worth paying.

How we tested the Tensor Extreme Conditions Mummy Sleeping Mat

LFTO and Trail Magazine Gear Editor Ben Weeks put the Tensor Extreme Conditions Mummy Sleeping Mat to test during a wild camping trip in the Scottish mountains.

Ben has been with Trail for over 10 years, and is a qualified Mountain Leader and Climbing Instructor. He loves thrilling scrambles and gnarly Scottish winter routes so is a master at putting technical gear and cold weather kit through its paces.

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