The Adjustable Heel Lift shoe insert helps relieve a variety of foot, leg, hip and back pain due to leg length inequality, heel spurs, plantar fasciitis or Achilles tendinitis. Simply adjust the number of layers from .16 to .375 to help correct balance of hips and back. High quality surface is treated to protect against UV, mildew and fungus. The rubber base helps prevent slipping inside shoes and absorbs impact to help reduce stress on the body. Use with athletic or dress shoes. Available in S, M or L. Not sold in pairs. Sizing: Small fits up to womenÛªs size 8 Medium fits womenÛªs size 8.5 plus and up to menÛªs size11 Large fits menÛªs size 11 plus