Train hard, train smart in TYR Hydroblade Fins. Engineered to promote short, quick movement through the legs and the feet, LFHYD fins help swimmers to create the natural flow of a flutter kick. With a 100% silicone construction and state-of-the-art comfort fit, the Hydroblade prevents athletes from feeling restricted as they move. In addition to an innovative heel strap design and convenient pull tab, each fin is also created with rounded edges to prevent discomfort in the fins foot cavity. When it comes to specs the Hydroblade is a stand alone piece of training equipment. In addition to channel side rails that amplify power in the water, all LFHYD swim fins also include an angled blade surface for upward kick resistance as you move. Plus, the Hydroblade comes in a variety of color and size options, making it an ideal choice for swimmers at every level.Color Coded Sizing for easy identification S (Men's Shoe 4-6 , Women's 5.5-7.5) - GreenM (Men's Shoe 6-7 , Women's 7.5-8.5) - YellowL (Men's Shoe 8-9 , Women's 9.5-10.5) - RedXL (Men's Shoe 10-11 , Women's 11.5-12.5) - BlueXXL (Men's Shoe 12-14 , Women's 13.5-15.5) - Black Please Note For female equivalent, size down 1-2 sizes.