Thermarest Sleeping Bags Explained
Posted by Mark Richardson on Jan 26, 2026
Vesper
Built to provide a featherlight pack weight and high-performance warmth, the Vesper 32F/0C quilt thrives during ultralight, backcountry adventures. The quilt uses thermally-efficient box baffled construction to ensure warmth and comfort in an ultralight package.
Vesper 32F/0C Down Quilt Regular (Comfort Limit 5°C, Weighs 459g)
Vesper 20F/-6C Down Quilt Regular (Comfort Limit 0°C, Weighs 585g)
*EN standards do not apply to quilts, so the comfort limit rating on this Therm-a-Rest is an estimate.
Hyperion
Hyperion are Thermarest's premium ultralight sleeping bag, made using the pinnacle 900+ Fill Power down contained within a mix of sewn through and box wall baffles. The Hyperion is so focussed on ultralight backpacking that they produced a limited quantity of 45F/7C bags which we have exclusive access to - with a total weight of 370grams the Hyperion 45s are the ideal mountain marathon or 2 season backpacking bag.
Corus
The versatile Corus™ Quilt offers essential comfort wherever you use it. Its perfect balance of functionality and warmth make it ideal for three-season backcountry adventures or for layering in colder conditions.
Corus 32F/0C Down Quilt Regular (Comfort Limit 5°C, Weighs 597g)
Corus 20F/-6C Down Quilt Regular (Comfort Limit 0°C, Weighs 786g)
*EN standards do not apply to quilts, so the comfort limit rating on this Therm-a-Rest is an estimate.
Ohm
The Ohm sleeping bags bring roominess and simplicity to ultralight backpacking. Filled with the highest quality 900+ Fill Power Down and built with box wall construction you know you are getting the highest warmth to weight ratios you can get. The package though is different - a rectangular and roomy bag without a hood and with the ability to open out into a quilt. If relaxed ultralight backpacking is you - this is your bag.
Questar
Questar sleeping bags are roomier than lighter bags and are filled with 650 Fill Power down, but that doesn't mean they aren't technical or focussed on performance. Thermarest have gone to great lengths to get the maximum thermal efficiency out of the shape and fill of the Questars. They are highly efficient spacious bags.
Parsec LT
When your plans are ambitious and your sleep is essential, the Parsec is your best friend. Made to deliver ultralight comfort for alpine nights, it’s now filled with highly compressible, warm and resilient 900-fill hydrophobic down. The soft, durable recycled nylon shell is easier on the planet, while the anti-snag YKK® zipper prevents wear and tear with easy entries and exits. The updated baffle structure and zoned insulation strategically locate more down in priority areas, while our down-lined Toe-asis™ foot pocket gives you a place to rapidly warm cold feet.
Vela 2-Person Quilts
Vela quilts combine 650 Fill Power down and box baffles to get the most warmth out of the materials, with a discrete footbox that works to either keep the quilt in place or for extra warmth where you need it. The Vela quilts offer a more relaxed sleeping experience.
Vela 32 Double Down Quilt (Comfort Limit 0°C* & Weighs 1034g)
Vela 20 Double Down Quilt (Comfort Limit -6°C* & Weighs 1342g)
*EN standards do not apply to quilts, so the comfort limit rating on this Therm-a-Rest is an estimate.
Polar Ranger
Designed in conjunction with renowned polar explorer Eric Larsen, the Polar Ranger -20F/-30C down sleeping bag is built for the coldest places on earth. The lightest and most feature-rich bag in its class just got better. It utilises cutting-edge box-baffled construction and is filled with highly compressible, PFC-free 800-fill Nikwax Hydrophobic Down™. This advanced down maintains its loft and warmth longer, even in the challenging conditions of extended expedition use in the arctic cold.
In this post we look at the various Thermarest Sleeping Bags and explain the differences and best use.