Mountain Equipment Mirrostat 7.0 sleeping mat review: A lot of bang for your buck

The Mountain Equipment Mirrostat 7.0 is a sleeping mat that delivers a superb warmth-to-weight ratio.

You get an official R-value rating of 4.5, which for some campers will be suitable for winter camping in zero or sub-zero temperatures, yet the weight is only 530g (regular size, including storage bag and repair kit).

That’s a better ratio than most other premium mats: the Sea to Summit Ether Light XR is 17g heavier but has a lower R-value of 4.1, for example. The Mirrostat 7.0’s warmth comes from its chunky 9cm thickness and internal Mylar reflective film for heat retention.

In terms of size, the mat has a rectangular profile, not a tapered mummy shape. It's particularly long (190cm), which is about 7cm more than most other mats, thus making it suitable for taller campers.

The 51cm width is pretty standard, if not slightly narrow, but the raised bathtub-style sides effectively prevent you sliding off laterally. The sleeping surface’s vertical baffles will feel a bit 'ridgy' and 'undulating' to some campers, but others will love the comfort levels – it’s all rather subjective.

The two-way, self-sealing 'Gas Mask' valve is modern and high-tech, enabling efficient inflation and deflation via Mountain Equipment’s Windsock – although the sack’s low volume meant it took us eight rounds to fully inflate the mat.

Comfort

The Mirrostat features seven offset baffles, arranged vertically along the pad. It’s around 9cm (3.5 inches) thick, providing good clearance from the ground and a pretty comfortable sleeping surface that I’d rate at around 8/10.

However, my personal preference is for a flatter profile, such as the quilted design seen in the Sea to Summit Ether Light XR or Nemo’s Tensor pads. For me, the pronounced, vertical baffles felt a bit ridgy.

Don’t get me wrong, I love a ridge in the mountains, just not one on my sleeping pad. But then, I have an odd sleeping technique, sleeping on my front with no pillow – so feel free to take my advice with a healthy pinch of salt!

It's worth trying out a few pad designs to get a feel for what suits you best, as comfort can be a very personal thing. Some people will undoubtedly like the way the vertical baffles hold them in place, while others may want something with a more even profile. It’s all dependent on the way you sleep.

Materials, shape and size

The outer fabric is a recycled, 20-denier plain weave polyester with the usual TPU lamination. The pad benefits from spot welded construction for extra durability. This is a good thing too, as Mountain Equipment has leant towards lightweight qualities over hard-as-nails ruggedness here. Mind you, it’s not like anyone wants their sleeping pad described as being as hard-as-nails.

However, it’s perhaps less robust than some of the competition, so it’s worth handling with care. The good news is that Mountain Equipment backs up the pad with its Product Lifetime Guarantee.

In terms of its shape, it’s ever so slightly tapered towards the head and toes, though its profile is generally rectangular. I tested the regular version, which is 190x51cm, making it quite a long and relatively narrow option – a design that’ll suit taller campers.

The long version is – surprise, surprise – even longer at 203cm, lengthy enough for many NBA players, though it’s no wider than the regular.

The Mirrostat is one of Mountain Equipment’s warmest and most expensive pads. The Aerostat Down series provides slightly better performance at a similar price, with R-values of 5.0, smaller packed sizes and more durable materials.

However, what you gain in performance you pay for in weight, with the regular-sized Aerostat Down coming in at an official weigh of 735g, which is a whopping 205g more than the regular Mirrostat 7.0.

There are also the Aerostat Synthetic pads, which are cheaper and more packable than the Mirrostat, but don’t quite insulate as effectively (4.0 R-value), while the regular version is still 140g heavier than its Mirrostat equivalent. For lightweight performance, the Mirrorstat is arguably the way to go.

Inflation and deflation

Like Sea to Summit’s Ether Light and Nemo’s Tensor families, the Mirrostat benefits from a clever twin-capped valve system, which Mountain Equipment have bizarrely called the 'Gas Mask' valve – evoking thoughts of the Blitz and, for my generation at least, school trips. When both caps are closed, no air can get in or out of the pad.

Opening the first, top-layered cap allows for inflation; opening the second cap removes any barrier between the inside and the outside, allowing for quick deflation.

You also get the customary micro-adjustment system seen on most modern mats – simply press your finger into the centre of the one-way top valve, and you’ll release little bursts of air, enabling you to fine-tune the mat’s air tension to your sleeping preference.

Another feature the Mirrostat has in common with Sea to Summit’s Ether Light series is the way the stuff sack doubles up as the pump sack. Mountain Equipment call this the Windsock – this time evoking thoughts of airfields (are ME trying to appeal to wild camping Spitfire pilots?).

As with the pad, the sack is long and narrow, and it took me eight sacks full of air to get the Mirrostat fully inflated – much less efficient than the three puffs needed for the Ether Light XR. Nonetheless, it’s still pretty decent and I was able to inflate the pad in a matter of minutes.

Warmth and R-value

The 4.5 R-value is seriously impressive given the pad’s low weight, making it more than suitable for 3-season use. You’d probably get away with it in November, but once temperatures begin to plummet in the depths of winter, a higher rated pad is preferable.

On the other side of the coin, ultralight alternatives will appeal more to gram-obsessed summer camping warriors.

Mountain Equipment achieves the relatively high R-value with internal Mylar. Mylar is a polyester film made from stretched PET that reflects infrared and leads to high heat retention.

The result is a pad with an enviable warmth-to-weight ratio that’s both lighter and warmer than much of the competition, including Sea to Summit’s Ether Light XR and Exped’s 5R.

Weight and packed size

I measured the packed down Mirrostat at 28x12cm, making it longer and thinner than most alternatives. However this is a positive thing, rather than a negative. Unlike some brands, which make it nearly impossible to squeeze your mat back into its tiny storage bag, Mountain Equipment have simply provided a larger, roomier bag with extra slack.

This makes it much easier to pack away the mat in the morning – a nice touch, enabling you to avoid the infuriating faff of a mat that won’t seem to pack down small enough to fit in its storage bag. On my scales, the mat clocks in at 530g in total including: the mat (477g), storage bag with integrated pump sack (49g) and the repair kit (4g).

Features

The baffles on either side of the Mirrostat are raised higher than the five central ones. This raised 'bathtub' design does its best to stop sleepers from sliding off. So, as long as you don’t pitch on an incline, you shouldn’t have a rude awakening in the dead of night.

Verdict

The Mountain Equipment Mirrostat 7.0 is a vertically-baffled, 3-season sleeping mat with a superb warmth-to-weight ratio – but the pump sack isn’t the most efficient.

Complete your camp setup with one of the best sleeping bags and the best one-person tents.

About the author

James Forrest is a prolific peak bagger and long-distance walker who’s one of the most high-profile outdoor writers in the UK. He writes regular features and route guides for Trail and has been one of our main gear testers for the last few years.

James is based on the edge of the Lake District so when he isn’t off on his latest crazy adventure or challenge, he’s walking in his local fells. James reviews every type of outdoor kit for Trail and is a real authority on everything you need for wild camping and packing light for a multi-day walk.