The double layer is absolutely effective for comfort and avoiding hot spots/blisters. Don't be dissuaded by the thin material. The fit is perfect with no bunching or excess material and rate it 5 stars. In 2004, I participated in the Susan G. Komen 3-Day Breast Cancer Walk from San Mateo to San Francisco CA wearing Wrightsocks. While training for the hardest event in my life, I wore Thor-Lo, Ultimax, DeFeet and Keene socks. Wrightsocks were recommended as the way to go and I'm so glad I did. No blisters!!! Wrightsock is the only sock I wear for walking, hiking, aerobics, etc.