Feedback on Montbell Spiral #3??

I have not used that exact bag, but I have used a few other Montbells, all the SS UL bags.

The weights are very close with all their bags, may be within an ounce or right on.

The ratings are right on too.

They do stretch and are very comfy, At least the SS bags are.

One thing about the #3 is it does not have a collar baffle. The #2 SS and lower and the #1 spiral and lower do have collars.

I just upgraded from a #3 to a #2 (25dF)mostly for that reason. Only an upgrade from 30dF to 25dF for the #2 SS but a collar can make a lot of difference.

The #1 Spiral is 2 LB which is not too bad for a 15dF bag. The #2 SS UL 800 is 1# 12oz.

Prolite has good prices on most of these bags.

Last somewhat cold night I spent out was this spring in a montbell SS #5 bag (rated at 40dF) in 40dF weather, outside no tent or bivy in just silk long johns and I was warm all night and that bag does not have a zipper baffle. That one is rediculously light at 1# 2 oz. I had my doubts and had an extra bag with me but it performed just fine.

I've tried both the spiral and regular SS #3, the regular hugs you a lot better and has a nice feeling fabric. the spiral #3 is much looser and the fabric is more coarse.

As I understand it, there is no elastic built into the Spiral bags. The "stretchiness" comes from the fabric being 'cut on the bias'… which simply means that it is being pulled on a diagonal relative to its natural grain. You can try it with any piece of fabric: try pulling the fabric on the diagonal between two opposing corners and it will stretch more than if you pull it vertically or horizontally. Fashion designers have used this fact for centuries when making eg. evening gowns which drape in a much more attractive way when the fabric is cut 'on the bias' (diagonal).

Anyway, I haven't tried one so can't comment on any other particulars. But I would certainly expect the "huggability" and the stretchiness to be considerably less than their regular "superstretch" line of bags. They will stretch more than bags from other manufacturers though.