The two brands that I have used are Camber and Arborwear. The Arborwear product is 100% cotton. It is composed of two layers of 13-ounch pre-shrunk cotton fleece. The Camber garment is also doublethick using a 90% cotton/10% poly blend. The Arborwear hoodie becomes softer after a few washings whereas the Camber garment retains a VERY subtle rigidity due to the polyester content. I wore the Camber full-zip hoodie over a heavy T-shirt and heavy denim button-down collated shirt paired with a lined denim trouser for a recent outdoor soup kitchen duty event. My body temp stayed at a very comfortable range despite the outside temp dipping into the 20s. I donned the Arborwear hoodie and matching trouser with only lightweight undergarments while in the cabin that had only a fireplace for heat.