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A quality performance Hydrophobic duck down bag with a relaxed, comfortable fit for regular outdoor use where comfort and warmth are more important than extreme performance and minimal weight. 
A quality performance Hydrophobic duck down bag with a relaxed, comfortable fit for regular outdoor use where comfort and warmth are more important than extreme performance and minimal weight. 

Rab Ascent 500 Sleeping Bag Left Zip

£167.00  £240.00  30% off
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Rab Ascent 500 Sleeping Bag Left Zip Information

Season : 2021S C OFFER

Brand : Rab

Code : QSG-68-LZ

Rab now use Hydrophobic Down in all their sleeping bags, this flurocarbon free treatment was developed in conjunction with Nikwax and although Hydrophobic Down is not waterproof it dries much faster, absorbs less water and retains loft far better than untreated down. The Ascent 500 is a 3 season season bag designed in a semi-rectangular shape that is user friendly for general camping or for those wanting a bit more room than a tapered mummy shaped bag.  The Ascent 500 offers fantastic value for money, quality construction and low weight for its performance. All Rab sleeping bags with left and right zips can be zipped together to form a cozy double bag.

Filled with 500g of 650 fill power 80/20 Grey Duck Down in a Semi-Rectangular shape which is optimised for the specific fill weight. The generous internal shape is cut to allow a more relaxed sleeping position without sacrificing the performance needed for general mountain and outdoor activities. The shape of the trapezoidal internal baffle chamber delivers a very stable structure that delivers a consistent distribution of down throughout the bag. Differential cut ensures that the space between the lining and the outer fabric is optimised for the specific filling and fill power. These two technologies combine to maximise the potential of the down to loft naturally and reduce migration resulting in greater performance.

The outer and inner fabrics are Pertex Quantum which is durable and lightweight and dries exceptionally quickly. Access is via a 3/4 YKK zip with an anti-snag baffle. An internal shoulder baffle helps to keep all the warmth in the bag and provides the ultimate in snuggly comfort. Both the hood and the shoulder baffle have drawcords.

Temperature ratings are used to indicate a bags performance but are subjective and can be hugely affected by many factors such as your health and metabolism, how much you have had to eat or drink, how active you have been, humidity and altitude, the type of shelter used and whether you are using a suitable insulating mat. Your sleeping bag is only as good as the mat that’s beneath it, we recommend EXPED mats for comfort and insulation.

The "Comfort" rating indicates the range at which a woman gets a full night’s sleep; the "Limit of Comfort" rating indicates the range at which a man gets a full night’s sleep and the "Extreme" rating indicates a range at which a woman is protected from hypothermia.  The Extreme rating is basically a survival rating and it is not advisable to rely on this for general use. The ratings we have published are Rab's "Sleep Limit" ratings which are calculated from EN13537-2002 and BS TOG ratings.

  • Pertex Quantum inner and outer fabric
  • 650FP European Duck Down
  • Rab fluorocarbon free Hydrophobic Down developed in conjunction with Nikwax
  • Wide mummy shape
  • Proportionally assigned differential cut
  • Internal YKK 3 coil zipped stash pocket
  • Wide foot area for extended comfort 
  • Left hand side ¾ length YKK 5 coil main zip
  • Anti snag zipper webbing tape
  • Internal collar and hood drawcord
  • Improved close fitting neck baffle design
  • Trapezoidal baffle chamber design
  • Angled foot box
  • Compression stuff sack
  • Cotton storage sack
  • Temperature tested to new European standard EN13537: 2012 (excluding 900 fill)
  • Hand filled in Derbyshire UK

How warm a sleeping bag do you really need? We’ve tried to help you by grouping our sleeping bags by their recognised comfort ratings. These are the ratings supplied by the brands that indicate the temperature at which you will remain comfortable whilst sleeping on an insulated sleep mat. After all, comfort is what you want when it’s cold and wet outside, and you’re all tucked up in your nice warm sleeping bag.

We always recommend that you choose your bag according to the coldest conditions you will experience; you can always unzip a bag if it is too warm, but trying to sleep when you’re too cold is just miserable. Bear in mind that we are all individuals, so we all feel the cold differently and that our own resistance will fluctuate depending on a whole load of factors, including how much we have eaten, whether we have consumed alcohol, whether we need a wee or what kind of mood we are in!

Sleeping bags do not generate heat; they only trap the heat we produce, so it is vital that you get into your bag when you are giving off warmth, don’t go to bed when you are cold, have a hot meal or a hot drink or do some brisk exercise to get you nicely warmed up.

Traditionally sleeping bag manufacturers provided their own temperature ratings based on their experience, the product's intended end-use and the perceived environment. However, each brand tested their bags in different ways, and it was hard to find a fair comparison between models. So, in 2005 a European standard for sleeping bag temperature ratings, EN 13537, was introduced to give consumers a comparable guide to sleeping bag performance across a range of brands and models. The ratings have four different temperature ratings to give you an indication of the bag's performance.

Comfort Rating: This is the temperature at which an average female should experience a comfortable night’s sleep. On average, women sleep colder than men, so this rating is some degrees above the "comfort lower limit" for a man.

Comfort Limit Rating: This is the lowest temperature at which an average male should experience a comfortable night’s sleep whilst laid down in a curled up position.

Extreme: This is a survival rating where the user is likely to suffer health damage such as Hypothermia. It should be treated with the utmost caution and not be relied on for general use.

However, the EN 13537 European Standard does not apply to down-filled sleeping bags with a fill weight of more than 800g; for those bags, you will have to rely on the manufacturer's experience and technical expertise, which is often more accurate!

Most reputable brands still use their own rating system alongside EN 13537, for instance, Mountain Equipment's “Good Night’s Sleep” and Rab’s “Sleep Limit”. These ratings are often the most accurate guide to the overall performance of a sleeping bag being used by an average outdoor enthusiast because they are based on years of expedition heritage, field trials, technological experience, and constant feedback.

But please bear in mind that all ratings are only a guide and, as mentioned earlier, there are a huge range of factors that can affect your comfort; if you are just not sure, it is always wise to go for a warmer model.

The biggest difference you can make to your overall comfort is to use an efficiently insulated sleeping mat. Once you get inside your sleeping bag, you instantly compress all the filling beneath you, greatly reducing its efficiency. Therefore using a quality sleep mat will ensure you are properly insulated from the cold ground, and you will be a lot more comfortable... Basically, there is no point in buying a top-quality sleeping bag if you are just going to lie down on the floor.

Technical Information

Weight: 1040g

Comfort: 1°C

Limit of comfort: -4.5°C

Extreme: -22°C

Rab limit: -6°C

Sizing Information

Max User Height: 185cm/72.8in (Standard) | 200cm/78.8in (Extra Long)

Shoulder Width: 75cm/29.5in

Hip Width: 65cm/25.5in

Foot Width: 50cm/19.5in

Packed length: 37cm

Packed diameter: 24cm

Professional Opinion

Words by Dom Haseldine

For a person that has laboured with a large synthetic sleeping bag for the last 5, years the Ascent 500 is an absolute treat!

So, first let’s cover the specs; the bag itself has a Pertex Quantum inner and outer with a filling of hydrophobically treated 650 fill-power duck down which is put into trapezoidal shaped baffles to help alleviate cold spots and increase thermal efficiency. It weighs just 1125g, comes with a cotton storage bag, a compression stuff sack and has a generous mummy shape. The comfort rating is 1C, the lower comfort limit is -4.5C and the extreme rating is a massive -22C.


Seizing the chance to review the Ascent 500, I swiftly planned a bivvy out in my back garden (Hay Bluff) at the end of November to allow the bag to flaunt its pros and cons. I checked the weather for Hay Bluff that evening, a cool 2 degrees with 50/50 chance of fog; a fair challenge for most down sleeping bags due to the wetter conditions. Although my synthetic bag has a comfort rating of -5C, it’s very large and took up most of a 50 litre rucksack; this is where the ascent 500 for me really showed its potential. It tucks neatly into the lower section of my rucksack in a dry bag with the compression stuff sack over the top, I wasn't going to take any chances. I ventured onto the Bluff, leaving the house at 6pm. It was dark by this point, the conditions were cold with a slight breeze, but clear.

blak n white

I had an enjoyable walk up to the Offas Dyke path, heading along the cats back towards Longtown to find a suitable space to bivvy down. Looking forward to jumping in the sleeping bag, it didn't take long to find a good spot which was suitably screened of from the wind. Swiftly laying out the bivvy bag, bed and sleeping bag, I packed my rucksack into a drybag before piling in for the night. Once in the bag, it didn't take long to appreciate the subtle differences between my two bags; the down gave an almost duvet feel with a noticeably warmer temperature. The two cinch cords at the top of the bag were also extremely beneficial, helping to trap the heat in and keep the cold out. The generous fit of the bag was a welcome change having tried several alpine bags which taper in and trap you like a straight jacket. The Ascent was exceptionally comfortable and completely in it’s element.

Apart from a lost or malicious horse stomping past very closely, I only woke up once in the early hours due to a moisture build up in my bivvy which had formed from the fog that had developed over night and dripped on my face; met office strike again! The sleeping bag surprisingly managed to put up a very commendable fight against this! The outer of the sleeping bag had patches of beading water with a few sections beginning to soak through slightly. This was most likely down to the ridges in the bed I was sleeping on collecting water and my weight pushing the bag into them. After re-packing the rucksack and having a quick bite to eat in the morning, I set off on my return journey.

Shortly after returning home, I got the bag out and laid it on the table, giving it a quick wipe where necessary. Very little moisture had absorbed past the face fabric and the down had hardly clumped at all, which was unexpected due to all the moisture in the air which had formed on the inside of my bivvy. If the bag had not had hydrophobically treated down I may have been a little more cautious, however the aim of these reviews is to push the Ascent past it’s comfort zone!


Overall the sleeping bag handled very well around its comfort limit with very little cause for concern, giving me a very comfortable nights sleep and coping well with the adverse weather conditions. Although the bag would be perfect for drier conditions given the nature of down, the Ascent handled it’s first damp outing without any issues. The large amount of space in the bag is a very welcome change from narrower, less comfortable bags and the cinch cords make it easy to warm yourself up after a cold slog up the Black Mountains.

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  • Do you have in stock either the Rab 500/700 Ascent sleeping bag with a left hand zip.
    Question asked by Graham on May 2 2021 8:34AM
    We have plenty of stock of both 500 and 700 Ascent sleeping bags with left-handed zips.
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