Everything in the  Western Mountaineering HighLite's design is intended to reduce weight and promote compressibility.

 

First, the .9 ounce ExtremeLite™ shell fabric. No other shell fabric is this light or packed with so many threads per inch.

Then there is the 850+ fill power down that gives the highest warmth to weight ration.

Then the one way #4 1/2 YKK coil zipper that is cut to half length and while the horizontal seams are sewn-thru, the vertical seams are baffled with 1 1/2" netting to allow the down to loft fully.

 

Finally, its efficient cut not only reduces bulk and weight.

 

At only 455grams total weight, no other bag is as light, as warm, as well made or as handsome as our HighLite. 

 

Shape	Size (ft/in)	Rating	Loft (in)	InsideGirth (in) shdr/hip/foot	Fill Wt.	Total oz	Stuff size (in)
Mummy	5'6"	32° F	3.5"	59"/51"/38"	7 oz	15 oz	6 x 10
	6'0"	32° F	3.5"	59"/51"/38"	8 oz	16 oz	6 x 12
	6'6"	32° F	3.5"	60"/52"/38"	9 oz	17 oz	6 x 12
Shape	Size (cm)	EN13537 Rating	Loft (cm)	InsideGirth (cm) shdr/hip /foot	Fill Wt. gram	Total gram	Stuff size  (cm)
Mummy	165	0°C	9	150/130/97	200	420	15 x 25
	180	0°C	9	150/130/97	225	455	15 x 30
	200	0°C	9	152/132/97	255	485	15 x 30

 

Editors comments:
The Western Mountaineering Highlite Sleeping bag is exceptionally light at only 455 grams total for the six foot bag. 

As far as I am aware, it is the lightest sleeping bag available that’s EN rated at zero degrees Celsius.
It is for this reason the Western Mountaineering Highlite is the first choice for all kinds of adventure racing, but it also makes for a very light May-September bag for the U.K. or for Summer Alpine trekking below 300 metres.

In addition, the pack size is about 5.3 litres.
Small sleeping bag = small pack = less weight
Editor: Adam