Thermarest Saros Synthetic Sleeping Bag

-5°C Comfort Limit (EN13537:2012), 879g of Synthetic eraLoft Insulation
Weighs 1340g (Regular size)
Code: SS15A561
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Thermarest's Saros is a weather resistant, 3 season, synthetic sleeping bag ideal for back packing and mountaineering in wet weather.

Thermarest says:

The three-season Saros sleeping bag is the perfect choice for backcountry trips that start with a shaky forecast.

EraLoft synthetic insulation offers warmth and quick-dry weather resistance that's ideal for backpacking and mountaineering in wet weather from spring through fall.

New fabrics provide a softer feel, while our SynergyLink Connectors and mattress integration ensure superior comfort with efficient warmth and the freedom to move as you like for the best night’s rest possible.

eraLoft Synthetic Insulation

eraLoft is a highly efficient and compressible synthetic insulation. Comprised of microfiber polyester, the core of each individual fiber is hollow, greatly boosting its heat-trapping capabilities while also shedding weight. Short-staple fibers also maximize loft and compressibility, while the inherently water-resistant fibers maintain warmth when wet, and dry faster than even treated down, making eraLoft an outstanding alternative.

Zoned Insulation

Zoned Insulation puts loft where you need it most – on top of you where it traps rising heat. Beneath you we use less fill, where your mattress already insulates you, and the value of lofted insulation is already minimized by compression. This is possible because our sleeping bags integrate with your mattress, keeping it properly oriented to maximize warmth and save weight.

SynergyLink Connectors

The key to our System Solution is our patent-pending SynergyLink Connectors. Integrating mattress and bag, they make sure you stay on your mattress while you roll freely for the best nights rest possible. Two elastic bands create a snug fit around any mattress up to 25 inches (63.5 cm) wide, keeping your bag centered and eliminating problems with sliding off your mattress or getting your bag twisted around you.

Thermarest's Saros delivers three-season comfort and all-weather peace of mind. It uses water resistant EraLoft which is a synthetic blend of three synthetic fibers that provide superior warmth, loft, and durability, ideal for backpacking and mountaineering in wet weather and temperatures down to -5C.

This full-featured bag is fitted with a draft collar and tube, as well as an anti-snag zipper, so you aren't struggling with your zipper after a long day of hiking. The external zippered pocket is a great place to stash a headlamp, and the adjustable hood can be cinched down to keep your dome warm throughout the night. Like all Therm-a-Rest sleeping bags, the Saros features SynergyLink mattress straps, which allow the bag to be securely attached too your sleeping mattress for a warm and comfortable night's sleep, no matter how much you roll around.

Over all this bag provides outstanding three season performance for a good price.

- Reviewed by BasecampGear

Read reviews here:      
  • Zoned Insulation (Shingled eraLoft w/ sewn-through insulated bottom)
  • SynergyLink Connectors integrate your mattress for optimal comfort and efficiency
  • Heat trapping draft collar and full-length zipper draft tube
  • Differential cut maximizes loft
  • Snag-free zipper
  • Cinchable hood
  • External zip pocket
  • Silicone DWR-Treated 20D Nylon Shell
  • Stuffsack and storage sack included


  • Weighs 1340g
  • Fits people up to 183cm
  • Girth Shoulder: 158cm, Girth Hip 147cm, Girth Foot Box: 102cm
  • Pack size: 20 x 46cm
  • EN Comfort: 1C, EN Limit: -5C, EN Extreme: -22C
  • Fill: eraLoft, 879g
  • Liner Fabric: 20D Polyester, Shell Fabric: 20D Polyester Ripstop


  • Weighs 1460g
  • Fits people up to 198cm
  • Girth Shoulder: 163cm, Girth Hip 152cm, Girth Foot Box: 102cm
  • Pack size: 33 x 49cm
  • EN Comfort: 1C, EN Limit: -5C, EN Extreme: -22C
  • Fill: eraLoft, 1020g
  • Liner Fabric: 20D Polyester, Shell Fabric: 20D Polyester Ripstop
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