Fatboy 400 Sleeping Bag

Temp. Guide

Comfort: ​-22°C (-7°F)
Limit: ​-30°C (-22°F)

Carry Weight

​​​​7.2 lbs (3.3 kg)


$232.99 CAD

The Fatboy 400 is huge! It has all the extra room you need for 4 season camping. And compared to other sleeping bags of the same size and temperature rating, this Fatboy is still the leader in compact/ lightweight.

36 in stock

Shape: RectangularCritical Layer Construction
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Just thought I’d drop a note saying what an incredible product you’ve made. I bought a Fatboy 400 for a winter camp with my Scout troop. Got to camp and realized I’d forgotten my sleeping mat. So all I had was my old wool army blanket to put between me and the snow. I’ll admit it took about an hour, but it slept the night almost too warm for the -20C night. The ground was hard, no mistake, but I was warmer than I can remember being sleeping on what was basically a wool-covered sheet of ice.
As a fan of winter camping, I look forward to many warm and comfortable nights in the bush. Thank you for making such a great product.

​~ Ian – Okotoks, Alberta

spectrum 2yagiback



Oversize rectangular with insulated hood


78″ long plus 15″ insulated hood
(198cm + 38cm)


42″ wide (106cm)

Carry Weight

​​7.2 lbs (3.3 kg)

Carry Size

51 cm long, 31 cm diameter (20” x 12”) 

Temperature Guide

Comfort: ​-22°C (-7°F)
Limit: ​-30°C (-22°F)
A few words on temperature ratings…


​Siliconized TrueLoft microfibre insulation with Critical Layer Construction

Outer Fabric

Polyester ripstop
Colour: Forest Green

Inner Fabric

Soft-touch Pongee polyester


#10, 2-way nylon coil self-healing zipper
High visibility fabric zipper pull

* all measures approximate

Critical Layer Construction

We use thermal body-mapping construction to place the insulation where it will do the most good. You already have an insulating sleeping mat below you, and most of the sleeping bag insulation that is below will be compressed by your body weight, making it inefficient. We move much of this insulation to the top of our sleeping bags where it will trap warmth from your body.

Then we add an extra layer of TrueLoft™ insulation in the core body area, from the neckline to below the beltline, to help achieve and maintain the temperature ratings. This extra layer of insulation will trap more warmth from the body than comparable sleeping bags, while adding very little to the weight, size, and cost of the sleeping bag. Think of it as putting on a jacket, the first thing we all do when we need to stay warm.

We call this Critical Layer Construction.

High quality TrueLoft™ micro fibre synthetic insulation traps more warm air between its fibers than traditional insulations with the same loft. This gives you a warm, soft sleeping bag in a compact and lightweight size.

  • Lightweight – some of the lightest weight insulation available
  • Compressible – siliconized fibres slide easily allowing for greater loft, compressibility, and softness
  • Breathable – insulation and fabrics breathe to allow heat-robbing moisture & humidity to escape
  • Extremely quick drying – hydrophobic qualities allow TrueLoft™ to absorb less water and dry quickly
  • Warm when wet – while drying, TrueLoft™ still keeps you warm, performing better than inferior insulations