Sea to Summit Ether Light XR Pro Insulated ASC Sleeping Mat – Long

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UOG TOP PICK – For High-Performance Winter Sleep Systems: With an R-value of 7.4, upgraded durability, and plush comfort at a lighter weight, the Ether Light XR Pro Insulated ASC is a standout mat for cold-weather trips where warmth, reliability, and packability are essential.

Sea to Summit says: 

The Ether Light mat design has achieved weight reduction by minimizing the curvature between weld points. Air Sprung Cells offer enhanced sleep support by providing greater stability compared to traditional, thicker mats. The innovative Thermal Core insulation ensures optimal performance in cold weather conditions without adding unnecessary weight.

Our Verdict

Building on the strengths of its predecessors, the Sea to Summit Ether Light XR Pro Insulated ASC Sleeping Mat delivers a notable upgrade in design and functionality for cold-weather camping. A key improvement is its impressive R-value of 7.4, up from 6.2, ensuring reliable warmth in sub-zero temperatures—ideal for winter expeditions.

The introduction of Thermal Core technology enhances insulation efficiency by reflecting infrared energy back to the sleeper, maximising warmth without adding unnecessary bulk. Additionally, the mat’s construction now features double the weld strength of previous models, significantly boosting durability for extended use in harsh conditions.

Comfort remains a priority, with the Air Sprung Cell design providing a generous 10 cm thickness. This structure offers a plush, stable sleeping surface, accommodating side sleepers and those who tend to shift positions. Despite these advancements, the XR Pro remains impressively lightweight and compact—around 25% lighter, packing smaller than earlier models.

With enhanced warmth, durability, and packability, the Sea to Summit Ether Light XR Pro Insulated ASC Sleeping Mat is a strong contender for those seeking a reliable, cold-weather sleeping system without excess weight or bulk.

– Reviewed by Ultralight Outdoor Gear

Features

• Stability is the key to comfort in an air mat. Sea to Summit’s Air Sprung Cell mats have dozens of air-filled ‘springs’ which provide stable support, making them the most comfortable mats out there.
• Constructed with superior materials and utilising cutting-edge lamination and weld technology, Sea to Summit air mats have excellent reliability. New Ether Light models have Thermal Shield construction, for enhanced insulation performance.
• The included stuff sack with integrated pumpsack and patented X-Press valve mean quick and easy inflation, adjustment and pack-away. The supplied repair kit makes for easy maintenance on the trail.
• The Contour shape provides additional width so you can roll over or sleep on your side; and it harmonises with
  Sea to Summit sleeping bags and liners.
• A layer of a reflective film is suspended between the dot welds of the mat. The film reflects back radiant warmth to the sleeper, and reduces air movement within the mat to a minimum, ensuring effective real-world insulation. Ether Light mats are highly regarded by lightweight, comfort – oriented users. Thermal Shield enhances the core values of these market-leading mats.
• Stuff sack with integrated Airstream pump.

Specifications

• Weight: 740g
• Dimensions: 198 x 64cm
• Thickness: 10cm | 4in
• R-Value: 7.5

Material & Construction

• TPU lamination and RF welds
• THERMAL CORE INSULATION

ASTM R-Value:

From 2020, there is a new industry standard for measuring the R-value (level of insulation) of sleeping mats – ASTM F3340-18. This new standard is the sleeping mat equivalent to the EN rating for sleeping bags.

You can now directly compare the R-value of mats rated using the ASTM F3340-18 with confidence that is a fair and accurate comparison between mats. In simple terms, the higher the R-value, the warmer the mat.

In general terms, an R-value below 2.0 is for summer use, 2.0 to 4.0 is for cooler 3 season use and 4.0+ is for winter temperatures. This will be also be dependent on your sleeping bag, how cold you sleep etc. Please contact our customer service team if you need advice on choosing the right mat for your activity.

Help & advice:

• The Ultimate Guide to Choosing an Ultralight Sleeping Mat
• Time-Saver Guide to Choosing a Sleeping Mat
• Sea to Summit Sleeping Mat Guide
• About Sea to Summit
• R-Value Explained