Not sure if anything changed in the making of this thermal crew, but the new thermal replacing the 820A is now Duofold by Champion KEW1. Fiber Content: 96% Polyester / 4% Spandex Bi-Ply Fabric.  Looks like the same material is used.

The matching thermal pants are now KEW2. I have these and they are exceptionally warm and they are thin enough that you can layer them with another pair of thin thermal pants. I ordered this matching crew because of the experience I had with the pants.  I can't rate this product yet because I haven't received it yet, but will give it 5 stars because of my experience with the pants.

I work outside for 8 hours as a security officer until 7 PM at night.  We have had a few days where the temps have gone down below freezing with wind. The pants did keep me very warm.  I do plan on layering them if need be when the temps as we head into winter get lower and lower.

What also is nice about this type of material is that it will not shrink under normal washing and wearing conditions.  The only way you can shrink polyester/spandex is washing or soaking it in extremely hot, almost boiling, water.  I always wash this type of clothing in cold water with minimal soap using DELICATE cycle of machine.  NO fabric softener ever.  Garment will last indefinitely.

I would highly recommend the set, top and bottom, for anyone who does stationary outdoor work in extreme cold temperatures.