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Sea to Summit Ascent ACII Down Sleeping Bag (-9C)

Sea to Summit Ascent ACII Down Sleeping Bag (-9C)
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The Ascent™ down mummy sleeping bag redefines what versatile means in a sleep system. Complex construction and high-quality down keep you warm when it’s cold outside, while the triple-zipper Free-Flow Zip™ system ensures you stay cool and ventilated when the weather warms.

Shaped to allow a natural sleeping position for comfort, the Ascent is light and compact enough to go everywhere your adventures may take you.

Weight: 1.10kg / 2.42lbs
Fill: 750+Fill Power ULTRA-DRY RDS Down
Fill Weight: 550g / 19.4oz
Compressed Volume: 6.2L

ULTRA-DRY Down 750+ Loft 90% Down Cluster Premium Duck Down certified Responsible Down Standard (RDS)

Free-flow zipper system: full-length YKK® #5 main side zip, half-length opposite side zip, and foot zip provides unparalleled ventilation and use as a comforter.

Vertical baffles over the chest to prevent down shifting as you roll over in your sleep.

Shaped hood, oversized draft collar, and zipper draft tube keep the cold out and the warmth in.

Internal pocket for phone / GPS / valuables.

Form a snug double sleeping bag by zipping to any Altitude™, Journey™ or Venture™ sleeping bag.

Includes lightweight Ultra-Sil™ compression bag and storage cell.

-4C Regular
-4C Long
-9C Regular
-9C Long
Ascent 1
Ascent 1
Ascent 2
Ascent 2
1.89lb / 860g
2.05lbs / 930g
2.42lbs /1.10kg
2.63lbs / 1.195kg
Comp Volume
4.9 L
6.4 L
6.2 L
7.8 L
Comp Sack
S - 10L to 3.3L
S - 10L to 3.3L
S - 10L to 3.3L
M - 14L to 4.5L
Fill Weight
11.6oz / 330g
13.1oz / 370g
19.4oz / 550g
21.7oz / 615g
Fits up to 
6 ft / 183 cm
6 ft 6 in / 198 cm
6 ft / 183 cm
6 ft 6 in / 198 cm
2.5 Season
2.5 Season
3 Season
3 Season



Warm enough for cold-weather use? Yes. The high-lofting down, technical hood, oversized draft tubes, and draft collar make the Ascent 25°F and 15°F true 2.5 – 3 season bags. For colder weather, you might choose the Ascent 0°F model and pair it with a high R-Value sleeping mat like the Comfort Light Insulated.


Really cool in summer temperatures? Yes. The Free-Flow Zip system means separate zippers on your left and right side and in the foot box. Open them for ventilation or to turn the Ascent into a fully-flat comforter.


Able to be zipped to another sleeping bag? The main side zipper can be zipped to the Sea to Summit Women’s Altitude, Journey and Venture sleeping bags – Regular and Long bags have the same side zipper length.


Sea to Summit Ascent Sleeping Bag

Be prepared for the unpredictable with our adaptable Ascent™ Series down sleeping bags. This range has everything you want for most adventures and then some. They’re lightweight, roomy, packable and surprisingly versatile.