blueseventy Thermal Neoprene Skull Cap - for Triathlon Training and Cold Open Water Swimming (Unisex) INSULATED - 3mm Yamamoto SCS coated Neoprene with full zirconium lining for insulation COMFORT FIT - Flexible central panel enhances fit. Strap provides secure fit maximizing warmth around the ears and chin PERFECT FOR - open water swimming and triathlon training GREAT MATERIALS - that are durable, comfortable, and keep you warm in chilly waters. Can use bright colored swim cap over the top for enhanced visibility LONGER SWIM SEASON - the blueseventy Thermal Skull Cap will allow you to get into the water sooner and swim later into the season