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

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UOG TOP PICK – For Year-Round Comfort and Efficiency: With improved Thermal Core insulation, a 10 cm plush build, and a quieter sleep surface, the Ether Light XR Insulated ASC offers dependable warmth and comfort for three-season use and moderate winter trips, without excess weight.

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

The latest iteration of the Sea to Summit Ether Light XR Insulated ASC Sleeping Mat brings a series of refinements that improve warmth and packability. The most significant change is the shift from down insulation to the new Thermal Core insulation, which uses multiple layers to reflect body heat while reducing air movement inside the mat, increasing thermal efficiency.

With an R-value of 4.5, this mat is capable of year-round use, providing enough insulation for cold conditions while remaining light enough for milder weather. While true winter expeditions may require additional insulation, it’s well-suited for three-season adventures and moderate winter camping.

At 10 cm thick, it retains the plush comfort of the previous model, making it an excellent option for side sleepers. The Air Sprung Cell construction continues to provide even support, preventing that ‘bouncy’ feel some air mats have. Inflation and deflation are quick and hassle-free, thanks to the XPRESS valve and integrated pump sack. A welcome improvement is that the mat remains quieter when shifting positions, making for a more restful night’s sleep.

With improved insulation and the same reliable comfort, this updated model refines an already excellent sleeping mat. It’s a strong contender for those needing a warm, stable, lightweight option for year-round adventures.

– 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: 688g
• Dimensions: 201 x 64cm
• Thickness: 10cm | 4in
• R-Value: 4.5

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