Mountain Equipment Aerostat Synthetic 7.0 Mat Review

Overview

The Aerostat Synthetic 7.0 is Mountain Equipment’s cold-weather sleeping pad, built under license from Exped’s welded-baffle construction and stuffed with 160g of Polarloft synthetic fill instead of down. It’s aimed at three-season and winter backpackers and mountaineers who want a genuine R-4 pad without babying it around sharp rocks or worrying about wet-down clumping — the trade-off being a noticeably heavier package than most “ultralight” insulated pads on the market.

Key Specs

Spec	Detail
Weight (Regular)	665 g (some retailers list 670 g)
Dimensions (Regular)	185 x 54 x 7 cm
Packed size	~23 x 12 cm (varies slightly by size)
R-value	4.0 (ASTM F3340)
Insulation	160 g Polarloft synthetic, welded
Fabric	30D nylon ripstop with TPU lamination
Construction	Exped-licensed welded baffles, vertically aligned chambers
Valve	2-way self-sealing Gas Mask valve
Inflation	Windsock inflator bag (doubles as stuff sack)
Extras	Repair kit included

Performance

Warmth. An R-value of 4.0 puts this pad solidly in three-season-plus territory, and it’s comparable in warmth to pads like the Therm-a-Rest XTherm or Sea to Summit Ether Light XT that get name-checked as its natural competitors. One long-term UK forum user reported using the Aerostat Synthetic 7.0 all year round in the Scottish Hills, describing it as probably a little heavier than other mats but never let him down. That lines up with what you’d expect from 160g of welded synthetic fill in 7cm-deep chambers — it’s not chasing a warmth-to-weight record, it’s chasing reliable warmth.

Comfort. The vertically aligned baffle structure (borrowed straight from Exped’s patent) is the same design used in Mountain Equipment’s down Aerostat, and reviewers of that sibling pad noted a depth of around 7cm makes this one of the thicker mats I’ve used, which again just seems to help with the sense of comfort. On the synthetic version specifically, one owner called it very comfortable, having slept on fairly uneven ground multiple times and calling it the most comfortable mat they’ve used, and added that they experienced no cold spots in the pad. That’s a meaningful data point since insulation migration and cold spots are the classic failure mode for baffled synthetic pads.

Inflation. The Windsock system pulls double duty as stuff sack and pump, which several sources flagged as a genuine convenience rather than marketing fluff — the ease of blowing up the pad is amazingly simple, with the stuff sack essentially turning into an air pump. It saves you from having to bag-inflate by mouth (which introduces moisture into the pad over time) without adding a separate pump’s worth of weight and bulk.

Durability. This is where the 30D fabric and TPU lamination earn their keep — and also where the picture gets mixed. On the plus side, a UK retailer selling both Mountain Equipment and lighter alternatives pointed out that you get a 30 denier fabric on these mats, making them more durable and puncture resistant than other mats we sell, while acknowledging this makes them a bit heavier overall, but it might be a price worth paying if you’re off on an extended trek or can’t guarantee smooth ground. That said, durability complaints do show up in the wild. One buyer’s first time backpacking with this mat, it failed him, developing two holes — one on the bottom and one on the top — despite finding no corresponding damage in the tent floor. A second reviewer using it on field trips reported using it on two field problems, one in the Arctic and one in Hawaii, having to make field repairs despite not sleeping on rock or anything sharp. These are anecdotal and don’t outweigh the generally positive comfort/warmth feedback, but they’re worth flagging — a 30D fabric is tougher than the 15D-20D shells common on true ultralight pads, but it’s still an air-chamber pad, not a foam block, and punctures happen.

Pros & Cons

Pros

• Genuine R-4.0 warmth rating suitable for winter and shoulder-season use
• Welded Exped-style baffle construction resists the insulation shifting that plagues cheaper synthetic pads
• 30D ripstop with TPU lamination is tougher than typical ultralight pad fabrics
• Windsock inflator/stuff sack is fast, keeps moisture out, and needs no separate pump
• Repair kit included in the box
• No down to manage — dries fast, performs fine if it gets damp

Cons

• Heavier than most R-4 ultralight competitors (665-685g depending on size, versus ~430-500g for pads like the NeoAir XTherm)
• Some reported puncture/durability issues despite the tougher fabric
• Limited independent long-term reviews available — data here is thinner than for more mainstream pads
• Premium price bracket similar to Exped, Therm-a-Rest, and Sea to Summit flagship pads

Who Should Buy This

This pad makes the most sense for cold-weather backpackers and mountaineers who prioritize reliable warmth and durability over shaving every last gram — think winter trips, guided courses, or anyone who’s tired of babysitting a down pad around condensation and pointy rocks. If you’re counting grams for a fast-and-light summer thru-hike, the weight penalty versus something like an XTherm NXT is hard to justify; but if you want a pad you can throw in a pack, inflate in under a minute, and trust through a genuinely cold night, the Aerostat Synthetic 7.0 fits that brief.

Verdict

The Aerostat Synthetic 7.0 delivers on its core promise — solid R-4 warmth, comfortable vertical baffles, and a tougher-than-average shell — wrapped in a smart Windsock inflation system. It’s not going to win any warmth-to-weight comparisons, and the scattered durability complaints mean it’s not bulletproof, but for cold-weather use where reliability matters more than ounces, it’s a sound, if unglamorous, choice. I’d put it at a 7.5/10: dependable and well-engineered, just not the pad to reach for if grams are your religion.