Dan Durston - of General Lightweight website says -The 'HH Warm' aka ProWool line of baselayers are all constructed of polypro and merino wool. You can see these polypro/merino garments here:
hellyhansen.com/products/filte…uct_type=HH_Warm|limit=30
The polypro and merino fibers are not blended together. There is an inner layer of polypro against your skin and then an outer layer of merino wool. I'm not too sure how the layers are attached together but it does work well. I handle all the warranties for our store and I've never seen an issue with this.
The product literature indicts the merino wool is for warmth, but I think it also helps keep you dry because polypro does not hold any moisture, so the moisture gets pulled away from the body into the merino wool (which can hold a bit of moisture) so you remain dry. Hopefully your other layers also breathe and continue to pull the moisture away from you.
I have picked up at 50% off at EMS a unknown brand of this product and its great ya a $20 undershirt for fall... well its hot.
hellyhansen.com/products/filte…uct_type=HH_Warm|limit=30
The polypro and merino fibers are not blended together. There is an inner layer of polypro against your skin and then an outer layer of merino wool. I'm not too sure how the layers are attached together but it does work well. I handle all the warranties for our store and I've never seen an issue with this.
The product literature indicts the merino wool is for warmth, but I think it also helps keep you dry because polypro does not hold any moisture, so the moisture gets pulled away from the body into the merino wool (which can hold a bit of moisture) so you remain dry. Hopefully your other layers also breathe and continue to pull the moisture away from you.
I have picked up at 50% off at EMS a unknown brand of this product and its great ya a $20 undershirt for fall... well its hot.
Be wise enough to walk away from the nonsense around you! 
