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Forclaz MT900 Down Sleeping Bag
This sleeping bag is warm and light thanks to the loft (800 CUIN) of the down used, and is also very compressible. Mummy shape and adjustable hood with good coverage and a drawstring.
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San Francisco, 735 Market St. Options
Select an available color and size to see options.
About this item:
- Comfort Temperature 50°F/10°C I Temperature Limit: 41°F/5°C
- Size L Weight: 1.5 lbs (700 g) I Volume: 4.9 L I Stuff Bag Included
- RDS ethical down with a fill power of 800 CUIN
- Water repellent: Outer surface of the fabric is treated
- Mummy shape, anatomical hood. 1 long zip on the left with a double slider
Product Features

Optimal temperature
Comfort Temperature 50°F/10°C I Temperature Limit: 41°F/5°C
Easy to transport
Size L Weight: 1.5 lbs (700 g) I Volume: 4.9 L I Stuff Bag Included
Sleeping comfort
Mummy shape, anatomical hood. 1 long zip on the left with a double slider
Water repellent
Outer surface of the fabric is treated so that water runs off the surface
Warmth
RDS ethical down with a fill power of 800 CUIN
Compatibility
non-twinnable sleeping bag
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Questions & Answers
Look for product information, frequently asked questions, opinions...
Question:
What is the difference in the 2 down mt900 sleeping bags? One is model 8575969 and the other is model 8618872.
Answer:
There is no difference other than the number. We switched codes and only had a couple left of the first code so priced it less to sell out quickly.
Don't see the answer you're looking for?
Product Customer Reviews

Used for bikepacking and camping trips in the mountains, the down is very compact and warm. Unbeatable quality for the price!
What a pity ! What is the point of Decathlon using 340 g of high-end down (800 CUIN RDS) and an anti-cold flap in this bag, if it is to spoil it with crossing seams which transform it into a thermal sieve? Especially since you master the manufacturing with trapezoidal compartments which avoid thermal bridges (this is what you have on the 0° comfort)... It's a real shame, because with 340 g of down 800 CUIN and a weight of 780 g in XL for 5.6 l, there was enough to have a great bag / a bit like this one https://cumulus.equipment/eu_fr/sacs-de-couchage-en-duvet- lite-line-400.html which is the holy grail for hikers who love 3-season ultralights! And this at an unbeatable price... Instead, after two nights spent in the mountains (Féclaz and Semnoz) I rushed back to Decathlon to change it for its big brother in 0° comfort, but which is over a kilo and 8.7 l in XL! Thank you very much Decathlon for allowing this exchange! To come back to this bag: it is probably OK for summer outings at 10° min, but as soon as the temperature drops (5°), the drafts at the seams are prohibitive!!! For my part, I had to put on my down jacket in the middle of the night to be able to stay in this bag until the morning at around 5°... It would take so few things to transform it into a magnificent ultra-light sleeping bag 2/3 seasons...
Alright
Perfect for those who are cold up to 1000m altitude in summer!
In terms of fit, it could be a little larger. I'm 1.84/80 and ordered size L
Flawless. Very comfortable and well designed duvet. Weight suitable for mountain trekking.
Suitable for sleeping in cabins or tents in areas
Insufficient protection against cold at 10 degrees
I regret buying a down duvet...
Very light and compact sleeping bag, which keeps you warm even when sleeping under the stars in the high mountains in summer (July/August). Also tested and approved in the high mountains in September, with a few extra layers of clothing.
Very practical to carry, but really tiny once forgotten in the pouch
Lightweight, comfortable down sleeping bag. Super pack size. Temperature data match. As a side sleeper you have enough space for your arms, even when the sleeping bag is completely closed. All in all very recommendable!
Used in bivouac in the Jura this summer. Good comfort even with slightly low temperatures for the season
Alright
Light sleeping bag, pleasant material, only tried on warmer days so far.
Additional Product Information
Composition
Filling: 90.0% Grey Duck Down, 10.0% Grey Duck Feather ; Lining: 100.0% Polyamide ; Shell: 100.0% Polyamide ; Carry bag: 85.0% Polyester, 15.0% Polyurethane ; Bag cover: 100.0% Polyester
What is the temperature rating?
All our sleeping bags display the temperature ratings, tested by an independent laboratory (AITEX), in accordance with the European standard NF ISO 23537 - 1. The comfort temperature rating is the lower limit at which the user in relaxed posture is generally in thermal equilibrium and feels neither too cold nor too hot (for a standard woman in normal conditions of use). Choose your sleeping bag according to this criterion.
What is the temperature rating (lower limit at which you feel comfortable)?
The comfort limit temperature is the temperature limit at which a person curled up in the sleeping bag is in general thermal equilibrium, neither too cold nor too hot (determined for a man in normal conditions of use).
An important clarification concerning the iso 23537-1 standard
In the context of this standard, the measurement protocol of a sleeping bag’s thermal protection uses a mattress with thermal resistance equal to an R-value of 4.8.This means that by using a less insulating mattress, the thermal performance of your sleeping bag will be lower.We therefore recommend you use an insulating mattress to optimise your thermal comfort.
Some advice to consider before you get into your bag
Dress simply (1 layer of clothing is enough). Warm-up your extremities: hats, gloves, socks, hand/feet warmers, rubdowns, etc. A flask of hot water can be used as a hot water bottle (as long as there's no chance of it accidentally opening!) Contract your muscles (70% of the energy consumed is converted into heat) but do it without moving as this could create a draught. Use a bag liner to optimize warmth and avoid washing your sleeping bag too frequently.
Style
The mummy shape optimizes thermal insulation (no loss of heat because there is not much air flow or draughts) and saves space, which means that your movements are restricted.Width at the shoulders 28.7 in. (73 cm), height at the feet 10.6 in. (27 cm) in size L.
Weight and dimensions
Size S: 19.7 oz. , user up to 5'2''. Bag dimensions: Ø 4.7 x 13.4 in. Volume 3.5 L. 9.1 oz. down/feathers.Size M: 21.8 oz. , user between 5'2'' in and 5'5''. Bag dimensions: Ø 5.11 x 13.4 in. Volume 4.2 L. 9.1 oz. down/feathers.Size L: 24.7 oz. , user between 5'5'' and 6' . Bag dimensions: Ø 5.51 x 13.4 in. Volume 4.9 L. 10.5 oz. down/feathers.Size XL: 27.5 oz. , user between 6' and 6'5''. Bag dimensions: Ø 5.9 x 13.4 in. Volume 5.6 L. 12 oz. down/feathers.
Functions
Anatomical hood with good coverage and drawstring adjustment.A baffle along the zip prevents heat loss.Double-slider zips for optimal ventilation.X-shaped compartmented structure, through-stitching.
The advantages of a duck down and feather filling
The filling power of down has 3 advantages for mountain sports:- Thermal insulation thanks to the air trapped in the down and feathers- Ultra low weight: down is lighter than synthetic wadding while offering the same degree of warmth. This saves even more weight in your backpack- Ultra-compressible
How to measure the fill power of a down and feather wadding?
The fill power is a measure of the down's thermal insulation capacity and its potential to ”trap” air. It is expressed in CUIN (cubic inches).So, down with a higher fill power (higher CUIN number) will occupy more space, trap more air and provide greater thermal insulation.For this sleeping bag with its 90% down / 10% feathers filling, the fill power is guaranteed to be 800 CUIN or more (international IDFB standard).
Storage instructions
To maintain its fill power, which is necessary for its insulation properties, store your sleeping bag by stuffing it in the mesh bag provided, feet first. Can be stored flat.
Origin
Imported
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Research and development
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Forclaz MT900 Down Sleeping Bag
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Heavy products return policy
If you return a product you will receive a refund for the purchase price plus any applicable sales taxes, less any non-refundable charges.
Decathlon will cover all shipping costs associated with your return except for items excluded from our return policy such as bikes, basketball hoops, snowboards, surfboards, tents, and other larger / heavier items.
Return costs for heavy products:
Weight Thresholds | Shipping within California | Shipping outside of California |
---|---|---|
> 9 lbs | $20.00 | $25.00 |
> 30 lbs | $50.00 | $65.00 |
> 100 lbs | $100.00 | $125.00 |
> 200 lbs | $200.00 | $230.00 |
If you return a product at any of our store locations, we will gladly help you find the best alternative product or refund you on the spot.
