These are single-lined, thin,2.5mm high stretch neoprene boots. The inside is lined in Metallite which makes them easy to slip on. The sole has an effective non-slip texture giving great grip on wet surfaces. They can be used with both full foot fins for greater warmth and to protect the skin from scratches and chafing, as well as with hard-soled boots, when using open-heel fins. When used in conjunction with hard-sole boots, warmth is considerably increased and if donned before your wet suit it is also easier to put on your suit. Non Slip 2.5mm boots have glued and stitched seams, are available in three sizes from small to large and are covered by a 12 month limited warranty.