These are single-lined, thin, high stretch neoprene boots. The inner is lined in metallite so they are easy to put on. The sole has an effective non-slip lining. They can be used with both closed foot fins to protect the skin from scratches and chafing, as well as with firm-soled boots, using open-heel fins These are single-lined, thin, high stretch neoprene boots The inner is lined in Metallite so they are easy to put on The sole has an effective non-slip lining They can be used with both closed foot fins for greater warmth and to protect the skin from scratches and chafing, as well as with firm-soled boots, using open-heel fins Warmth is considerably increased and it is also easier to put on your wetsuit S - EU 38/39 M - EU 40/41L - EU 42/44XL - EU 45/46