Designed for multi-day excursions in inclement weather, the Furnace is one for those wishing to push the three-season boundaries a little further out.

An efficient mummy with a vaulted foot, the bag rolls nicely with you as you turn over and is spacious enough to pull both knees up without feeling restricted.

Polyester taffeta fabrics are used throughout. During testing they became static charged, but with use this will settle down. The fabric comfortably moves moisture and works efficiently with the water-repellent 550-loft ProDown goose down to retain warmth. ProDown dries more quickly than untreated down, making it a good choice for damp weather conditions that can be experienced on multi-day trips.

Synthetic Heatseeker anti-compression insulation is used strategically on the underside of the bag to create a thermal barrier against conductive heat loss, further increasing the bag’s low-temperature performance.

The side zip (by far the best tested) runs smoothly throughout its entire length, and is backed by an excellent draft tube. To aid starting the zip from the bottom end is a decent-sized fabric tab, which is easy to grab when you’re fumbling for it at night.

The hood is roomy and surrounded by a draft collar, but the poorly positioned opening sits too low so that when drawn up it leaves your chin exposed and struggles to stop warm air escaping. Two different cords, top and bottom, are used to adjust the opening, and while they’re super secure when cinched up through the one keeper, they are thin and too fiddly to work with in the dark.

Although vaulted and spacious, the foot box feels square and doesn’t always allow feet to rest in the most relaxed position.  

Although a little heavy at 1200g, this is a serious yet comfortable bag that nicely bridges the gap between general and enthusiast’s use.