This top is made from Chillproof material and provides the ultimate versatility by being able to zip up for 100% warmth and protection, or zip partially down when the sun comes out or your work rate goes up. The longsleeve design provides maximum warmth and full sun protection. Perfect for all paddle watersports and power watersports like jetski where you need the security and ventilation options of a half-zip design. It also has a high collar to keep your neck area warm.