The Harmony Clearwater TTD Sprayskirt has a patented tunnel system that makes it one of the most versatile recreational kayaking skirts on the market. TTD stands for Tunnel Tie Down. It’s a patent-pending system that allows you to drop the tunnel of your skirt down to the deck in a compact roll for ventilation and improved access to the interior of your boat. Made of 210 denier nylon fabric coated with polyurethane, this sprayskirt is lightweight and durable and fits conveniently into a provided stuff sack.