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May 2018 Issue
Home / Gear reviews / Sleeping Bags

Therm-A-Rest Space Cowboy 45

Therm-A-Rest Space Cowboy 45 ($299.99 / 550g (regular) / 11℃ - comfort rating)



Our Rating:


At a glance

Plusses: Will insulate when wet, lightweight, packability and price.
Minuses: Limited seasonal use.

Features: Small and light enough (550g) to take almost anywhere, the synthetic filled Space Cowboy packs away like a down sleeping bag and weighs less than half a kilo – lighter than most down bags. It uses a warm-when-wet insulation, zoned to put the loft on top of the bag where it doesn’t get compressed by your body – this works on the assumption the user will be lying on a mattress. Warmth is retained further with a ‘Thermacapture’ lining that reflects radiant heat back onto the body. The bag’s mummy shape reduces dead air space and the drawcord hood cinches tight around the head. Removable mattress connectors allow the bag to be attached to a sleeping mat to prevent roll-off during the night. These work well and are easy to remove for those who don’t need them. A three-quarter length zip can be opened top or bottom to allow some ventilation options.

Fit: The mummy shape is roomy enough to not feel constricted and the hood is comfortable when pulled tight. 

Comfort: The bag’s inner is lined with a polyester taffeta fabric that is soft and luxurious, but also gives a slightly clammy feel when you first climb in. The bag has a comfort rating of 11-degrees so I never felt over-hot in it and could regulate my temperature with the side zip if need be.

In use: The small pack size and light weight make this an easy bag to carry. Even though there’s not much insulation – just 250g – it kept me warm on two hut nights in Tararua Forest Park, including one night at 1100m while a storm raged outside. The mat connectors were useful and ensured I didn’t roll off the mat during the night when not sleeping in a bunk.

Value: This is an inexpensive bag when compared to a down-filled bag and is priced near the top end for synthetic bags – but few, if any synthetic models, are as light or as compressible.

Verdict: I can take or leave the mattress connectors, but everything else I like – its weight, its packability (nearly half the size of my usual down bag) and the insulation is enough for any summer or early autumn tramp – wet or dry. Just use a sleeping bag liner and wear an extra layer to lengthen the season.

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