The Pedifix Inc Plantar Fasciitis Relief Sleeve relieves heel & arch pain by reducing stress on Plantar Fascia Ligament. It promotes healing, enhances circulation and helps minimize the effects of inflammation. Wear them under or over your socks daytime or nighttime. It features a knitted pattern and subtle nodules to relieve pain and swelling. Sizing: Medium is for a foot with 9" to 13" arch circumferance and a large is 11" to 15". The XLis for 15" or more in circumferance. Packed one sleeve per box.