Traditionally patients suffering the excruciating pain of Plantar Fascitis would use a plastic night splint. The Ortholab Night Splint Sock offers a a lightweight more comfortable alternative to the treatment of this condition by gently stretching the plantar fascia, Achilles tendon, and calf muscle. This gentle stretching while resting prevents the plantar fascia and Achilles from tightening, relieving the pain associated with the tightness of first steps. The degree of plantar fascia stretch is adjustable, so the sock can be used as part of a gradual rehab programme. C an be worn with or without a sock underneath. Socks are sold as single units. The sizes are as follows (US shoe size): Small (men\'s 5-7, women\'s 5-9 shoe sizes) Medium (men\'s 8-10, women\'s 10-13) Large (men\'s 11-15)