The NEMO Tensor 25R Insulated sleeping mat is a bit of a mouthful, but it saves grams where it counts, without sacrificing warmth or comfort. Our Editor Tim gave it a road test over the past few months – let’s just say he was baffled.

Back in 2014, whilst preparing for a backpacking trip in Patagonia, I bought my first air mat. My best mate showed me how he could inflate his from the size of a 1 litre Nalgene into a fully fledged air mattress. It was witchcraft. I went out and bought one the next day and I’m not kidding when I say I haven’t hiked with anything else since.

So air mats are sick; they offer comfort and warmth, you no longer wake up with a dead shoulder, and they take up way less space than closed-cell or self-inflating mats; do I have the right to get picky?

Well, yeah. Air mats can be loud when rolling around in the tent, hard to take care of, or simply not warm enough.

US brand NEMO (I think they like the all caps thing) is claiming that their NEMO Tensor range is super light, warm, quiet and comfy all at the same time, thanks to a bunch of tricky tech and materials. Sounds bonza! I put it to the test.

tim ashelford, nemo tensor 25r insulated review, sleeping, air pad, gear,


For this review I was sent a NEMO Tensor 25R Insulated. This means that it’s the regular length and thickness but 13cm wider than their regular model. Because I’m worth it.

The Tensor mats are 7.6cm thick, which is pretty thick for this kind of mat, but I found out later that this was only part of the reason that I found it so astoundingly comfy to sleep on.

Inside the mat there’s a low-stretch Spaceframe™ that helps support the edges of the mat and stops them collapsing; it also helps get rid of the bouncy feeling some mats get and stops you bottoming out when moving around. The end result was that, unlike other mats, I started backing off inflation to about 90% – there was no reason to overcompensate for a lack of stability with brute inflation. Pretty neat.

tim ashelford, nemo tensor 25r insulated review, sleeping, air pad, gear, tent, red room

Baffles in their natural habitat.

The mat has subtle lateral baffles that are very nice to lie on; they’re slightly undulating and just a little bit quilted, like those leather benches in art galleries.

Slip note: Lateral baffles are better at helping you to not slide down to the bottom of your tent at crappy campsites.

NEMO claim that their Spaceframe™ construction and suspended insulation (more on that later) keep the noise down and that’s kind of true compared to the competition, but it’s still definitely not whisper-quiet when rolling around.

I’d love to see outdoor companies find a solution for air mat noise because it makes going for a stealthy pee sound like a quarry on open day.

Weight & Size

My Tensor was a 25R, meaning that it was wider than regular at 64cm; the regular width is 51cm which is pretty standard for mats but I like to roll around in my sleep. I found the regular 183cm length more than enough (the long doggo comes in at 193cm).

tim ashelford, nemo tensor 25r insulated review, sleeping, air pad, gear, packed

The mat easily packs into a drawstring bag and takes up just more space than a 1-litre water bottle, just like that first mat I was shown years ago – the impressive thing is that this mat is just as insulated but comes in at only 540g – seriously light.

There’s a solid range of sizes to choose from in the Tensor range so you can customise your mat choice. A shorter, lightweight “mummy” mat comes in at half the weight of my test model. I’d always recommend getting yourself an insulated version though; it only adds a fraction of the weight and it’ll still be fine for summer (it can’t be too warm, think of your mattress at home!)

Ease of Inflation

The Tensor mats inflate via these small valves that stick out like a little dongle; I’ve got mixed feelings about these.

For inflation by mouth this valve is definitely easier to wrap your lips around then the flush valves common on many other mats and it didn’t take more than a few minutes to blow up. It’s easy to make small adjustments to please even the most softcore adventurer and thankfully, NEMO have added a big fat separate dump valve to easily let the air out in the morning.

tim ashelford, nemo tensor 25r insulated review, sleeping, air pad, gear, inflation dongle

Lil’ dongle

Unfortunately inflation by mouth has fallen out of fashion because a) it blows and b) it’s bad for the mat because your lung-breath is super moist. Even after a single use I saw moisture buildup inside the mat. I get that this mat is designed for those counting their grams, but is it worth sacrificing the life of your gear? I don’t think so.


They do make a baggy: NEMO have this thing called a Fillo™ Bello (…?) that works as a pump, pillow and dry bag. I didn’t have one for this test but I’d say getting one when you buy this mat is almost essential; it pretty much neuters anything bad I had to say under this heading.


NEMO don’t publish “R” ratings with their sleeping mats (they reckon they’re dodgy) and if we’re being honest, we’re just converting those into a vague temperature range anyway. The min. temp. listed on my Tensor 25r Insulated was -9°C, more than enough for any Aussie conditions, though you might want to chuck a closed cell mat under it if you’re camping on snow.

The Tensor was toasty as. I found myself sleeping in just an inner sheet at temps where I’d definitely have been deep in my sleeping bag on inferior mats. For such a lightweight package this was pretty incredible – you could easily use this mat year ‘round in Aus and you’d probably be fine in New Zealand as well.

tim ashelford, nemo tensor 25r insulated review, sleeping, air pad, gear, you can see the metal

The floating Thermal Mirror™ metallic layer with holes for the Spaceframe™ construction. When did the outdoors get so nerdy (and copyrighted?)

NEMO creates this warmth by suspending their Thermal Mirror™ metallic layer in the middle of the mat. It reflects radiated heat (up to 90%) like a space blanket but you don’t hear it as expected ’cause it’s kinda floating. My mat also had an incredibly thin (see pic) layer of Primaloft® to help insulate from the cold ground.

tim ashelford, nemo tensor 25r insulated review, sleeping, air pad, gear, insulation

It’s pretty hard to get a shot of the Primaloft®. It’s that white fluffy stuff.


Weight and durability are inherently fighting each other and NEMO’s Tensor 25R definitely favours weight saving. The fabric is only 20D (denier is a measure of fibre thickness) which is a fair bit less than many competing brands. That being said, the fabric seems tough enough and all of the gluing and finishing has been done to a high standard. As long as you keep the mat in the tent for use I’m sure it’ll last you many years.

I didn’t like the way you had to twist and push the inflation valve close it, it felt like I was putting stress on the fabric and there’s the risk of snagging its little dongle head if you’re not careful. I’d also definitely get one of those pillow inflator things to extend the life of this mat.

If the possum poo hits the propeller there’s always the included repair kit and a lifetime warranty from NEMO to help you get cushy again.

tim ashelford, nemo tensor 25r insulated review, sleeping, air pad, gear, red room

I’ve started referring to my tent as “The Red Light District”

So Am I Baffled?

The NEMO Tensor 25R Insulated was the comfiest air mat I’ve ever slept on. The stability, subtle baffles and warmth were all extraordinary for such a lightweight package and I can feel myself descending ever deeper into the mushy embrace of softcore backpacking.

I reckon there’s some room to improve the inflation dongle and fix the noise issue but compared to the competition NEMO are doing alright. Pricewise you’re looking at about $250 for one of these mats, which is pretty standard for what’s being delivered, but you’ll be happy you spent the money when you wake up feeling el fresco. Go on, you’re worth it.

This review was not paid for but the author was allowed to keep the Nemo Tensor sleeping mat after the review.

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NEMO Tensor 25R Insulated
"The NEMO Tensor 25R Insulated was the comfiest air mat I've ever slept on."
Weight & Size
Ease of Inflation
An extraordinarily comfortable night's sleep
Warmth without the weight
Spaceframe gives the mat heaps of stability
Inflation dongle has room for improvement
Not as quiet as expected