I just received this North Face Mittens with Bergans Helium 30L rucksack.The outlook and material content of the mittens are very good. After rough estimation, there would be about 160-170 grams of 800 fill power goosedown that excel other similar mittens of other brands. The size is a little bit loose for me although North Face size chart says that S size suits for upto 18 cm length hand.But there is no circumference size at knuckle.To my understanding, S size would be around 18-19 cm.
I still not yet have the chance to use it in extreme cold weather that I do not know its warm protection performance (thermal efficiency).It all depends on the thickness of the insulation around the fingers and palm.
It seems to me that the thickness is a bit less than the expectation (2 cm all round at least), especially the finger portions (tips to knucke) are less dense and bulgy comparing with similar fill power goosedown other products.Usually, that part feels cold first as only very small blood vessels are there together with size effects.
Comparing with the Montbell 750 fill power, 90% goose down mittens, Montbell one has the simialr bulge around the hands but very bulgy at the forearm portion that is waste of goosedown.It should be packed more in the finger and palm areas that are the most important parts that the mittens to keep warmth.