Lightweight night splint sock that relieves Plantar Fasciitis by stretching the sole of the foot during sleep. Ideal Uses Relief of Plantar fasciitis. Details Which size do I need? Sold individually (not in pairs). Fits left or right foot. Measure around the widest point of the Calf. Regular uo to 40.5cm (16") Large 40.5-53.5cm (16-21") How does it work? It's so simple. Research has shown that stretching the Plantar Fascia (sole of the foot) at night helps to relieve Plantar Fasciitis and that's what the Strassburg Sock does. It fits like a normal sock but the toes can be pulled back towards the knee using a Velcro and fabric strip. This puts the ankle and foot in a 'dorsi-flexed' position that stretches the Plantar Fascia. When the Plantar Facia is stretched for a sustained period during the night the tissue heals in a better position. This can reduce and relieve the symptoms of Plantar Fasciitis and heel pain.