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A compact, minimalist ultralight mat that prioritises efficiency for warm-weather use
Rab says:
We’ve slashed weight and volume wherever we can with the Ultrasphere 1.5, crafting the definitive sleep mat for when every gram counts. It combines an ultralight fabric with a new weight-saving construction that uses innovative offset air chambers to trap heat within the mat, keeping you warm on wild overnights without the need for bulky insulation. Highly comfortable and supportive, the Ultrasphere 1.5 is the ideal foundation for thru-hiking, summer bikepacking, and multi-day mountain runs.
Our Verdict
The Rab Ultrasphere 1.5 Sleeping Mat is built with weight and packability firmly in mind, weighing in at 316g, it's best suited to summer trips, reflected by its 1.4 R-value.
The tapered shape keeps bulk to a minimum, and at 8cm thick, it feels stable and comfortable, making it good for both back and side sleepers.
The included pump sack is efficient and straightforward to use, weighing 68g, and makes setup quick while avoiding moisture build-up inside the mat.
The mat looks impressively small in the supplied stuff sack. Though getting it back into the bag can be frustrating, especially when packing away quickly in the confines of a small tent, it makes more sense to use a simple stuff sack or an elasticated band instead.
Overall, this is a focused ultralight option that offers good support for warm-weather trips.
- Reviewed by Ultralight Outdoor Gear
Features
- The new weight-saving construction uses offset air chambers to trap heat and keep you warm.
- Comfortable tapered mummy shape that eliminates unnecessary bulk.
- Soft, exceptionally lightweight 20D fabric.
- When it’s time to pitch for the night, the two-way valve and inflation sack make camp setup quick and easy.
- R-value: 1.4.
- Thickness: 8cm.
- Packed size: 18x9cm.
- Roll-away stuff sack with repair kit included.
Specifications
- Weight: 316g
- R-Value: 1.4
- Thickness: 8cm
- Packed size: 18x9cm
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.
Material & Construction
- 100% Polyester Inflatable Mattress
