Rab Ascent 500 Sleeping Bag Review

Discover the test of the RAB Ascent 500 sleeping bag: three-season sleeping bag. Garnished with hydrophobic duck feathers with a filling to 500 g, it turns out to be a good choice for the first purchase of down technical.


The RAB Ascent 500 is a green sarcophagus pattern for three seasons (spring, summer, autumn). Comfort temperatures are 1 ° C, with a comfort limit of -5 ° C and an extreme of -22 ° (according to EN13537). Designed and filled with down coming from England (the textile comes from China), this product is well finished and of quality. Ascent 500 is part of the Ascent range, which includes four downs, the 300, the 500, the 700 and the 900. The filling is different each time, denser, therefore, warmer each time the number increases. RAB also offers all sorts of models, from very light to a weekend at the sea between buddies down to the expedition to the Roof of the World.


Program 3 seasons
Color Green
Outdoor fabric Polyamide Pertex, Microlight treated water repellent
trim Duvet Hydroformed duck Nikwax FP 650
Lining polyamide Pertex, Microlight 30D
Zip Zip YKK 3/4 double direction
Construction Differential outer / inner section
Maximum user size 185 cm
Comfort temperature + 1 ° C
Comfort temperature limit -4.5 ° C
Extreme temperature -22 ° C
Filling weight 500 g
Total weight 1060 g
Recommended retail price 249.95 €


Our test of the RAB Ascent 500


Test conditions

  • •  Testeuse:  Maud Devouassoux
  • •  Tested in size:  Regular (L)
  • •  Test conditions:  Tour of Mont Blanc for 6 days, then a week in Finland in Hossa National Park. The weather was mild in France, with rather warm nights. In Finland, it was more humid (around 10 ° C).

Thermal performance

Sleeping bag: RAB Ascent 500 © Maud Devouassoux
© Maud Devouassoux

The down reveals three temperatures: a comfort temperature at 1 ° C, a temperature limit of comfort at -4.5 ° C and an extreme temperature at -22 ° C. This means that up to -5 ° C, you can sleep in this fluff, possibly with a little wool if it is chilly and a risk of waking at night with a slight cold. At 1 ° C the night will be perfect but at -22 ° C, we can spend the night without sleep, but without ending in hypothermia.

The duvet is filled by hand with 500g of duck feathers (650 FP) hydrophobic. The duck down has an insulating power twice that of synthetic down. On the other hand, natural feathers lose their effectiveness once wet (unlike the synthetic that remains effective even wet), so be careful never to wet your down.

There is virtually no loss of heat. Indeed the partitioning is realized in trapezium. This results in the creation of closed, hermetic compartments which prevent the down from moving, agglomerating in certain parts of the bag. There are no through seams, so no cold spots or heat loss through the seams. However, it can be seen on the photos taken from the inside of the down that the filling is more optimal in the middle of the compartments than on the side. Feeling, it does not change anything, the down remains very hot. There is also no heat loss at the zip, because it is lined with a thick layer of down inside.

In addition, RAB uses Pertex Microlight fabrics. This material is top as it is water repellent, breathable and windproof. As a result, the down remains dry (water repellent effect), lets the water vapor pass (breathing effect) and is well insulated (the wind does not remove our warm little layer). Natural feathers remain dry and retain their swelling power.

I never got cold in this fluff, but the summer nights were never very cold. But all the technologies put in place are of qualities, and this is what is done best at the moment, so I have no doubt about the thermal performance of the down.

Rating: 4_star(4/5)

Manufacturing quality

As seen previously, the manufacturing quality is optimal. The choice of materials (Pertex Microlight fabrics) and partitioning techniques (trapezoidal) make this down a real source of heat. The material is resistant to abrasion and is water repellent (but not waterproof, careful). It is quite possible to sleep under the stars in summer, if the temperatures are not too cold. The fact that the material is windbreak is a real advantage: one keeps in heat.

The zips are YKK, which is best done in zipper. The opening is three-quarter, on both sides, one keeps the feet warm. There is an anti-snag tape at the top and bottom, which is handy to avoid getting hurt during a difficult awakening. As for quality, nothing to say is solid. And if it breaks, it’s easy enough to fix.

The seams look resistant, I did not have any particular problems to notify during my tests (no flying thread to this day, only a few feathers that are removed from time to time, but nothing abnormal).

There are two small straps at the base of the sleeping bag, to hang it on a cord.

Note: 4.5_star(4.5 / 5)

Sleeping bag: RAB Ascent 500 © Maud DevouassouxSleeping bag: RAB Ascent 500 © Maud Devouassoux

Sleeping bag: RAB Ascent 500 © Maud Devouassoux

Interior Comfort

The sleeping bag is very comfortable as it is large. The feeling of heat is immediate when you slip inside. The fabric does not stick to the skin, it is soft and breathable. The mummy shape is effective, the heat is well distributed throughout the body. The hood integrally covers the head and even part of the face if desired. The collar is adjustable, just like the hood, thanks to a cord that is locked. It is easy to loosen everything when you are in the down, caulked from the cold. The three-quarter zip always keeps feet warm, and the wide form leaves space. All the zipper is protected from the inside thanks to an anti-snag fabric, likewise on the top and bottom of the closure. Still a good point for comfort,

For maximum sizes, the down is for a length of 185 cm, a shoulder size of 75 centimeters, hips of 65 centimeters and a foot of 50 centimeters. I was comfortable because I am much smaller than the maximum allowed templates (size 170 cm, shoulders 44 cm, hips 35 cm, foot 24.5 cm). I swam a bit in the down, so I will not dwell on the size. But the down looks great overall, no doubt that even a strong man can be at ease (or someone 2 meters can be comfortable in the extended version).

On the practical side, the down is available with a zip for left-handed, in woman model (lighter of 40 grams because smaller) and in extended model (for the people of 2 meters maximum, weight of the down 1125 grams). And for couples or for very cold nights, it is important to know that all the downs of the Ascent range are compatible with the zippers, so they can be paired.

Rating: 5_star(5/5)



With a weight of 1060 grams for comfort at + 1 ° C, down is average. Storing the sleeping bag in its compression bag is very easy; the bag is large. There is only one compression bag that is attached to the storage bag: first we put the down in the storage bag (size when ordered 19 x 31 cm, 9 liters) and then we put the straps correctly and we compress the down. I do not find it very practical, you can not compress the bag as much as you want (different opinions exist within the team of testers). Once compressed to the maximum, the down is 19 x 25 centimeters. The gain is not very high. The cover has a handle to pull down the down, which is very convenient.

Rating: 4_star(4/5)

Sleeping bag: RAB Ascent 500 © Maud DevouassouxDSC_1559

General overview

The Ascent 500 sleeping bag from the RAB brand is a very good down, which is warm and good manufactured. Duck feathers have a very important swelling power that gives a quick feeling of warmth. The technologies put in place (trapezoidal partitioning, no through seaming, protection of the zipper from the inside …) make it possible to conserve this heat produced. Materials (YKK zip, Pertex Microlight fabrics) and manufacturing processes (hand filled fill) are optimal for the sleeping bag to last in time. The price is quite decent and it is a very good buy for a first quality duvet.

Rating: 5_star(5/5)

We liked

We liked it less

• The added warmth: a real pleasure
• The quality of manufacture: it will last for a long time
• Compression cover integrated in storage bag

The notes of the draft

Price-performance ratio: 5_star(5/5)

Thermal performance: 4_star(4/5)

Manufacturing quality: 4.5_star(4.5 / 5)

Inside comfort: 5_star(5/5)

Overall dimensions: 4_star(4/5)

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