Premium Warmth. The Drylock series is the warmest, most technical wetsuit in the Xcel lineup, made for the most extreme conditions. The Drylock series offers water-tight construction, with our new Thermo Dry Inferno (TDI) interior from the chest to the knee, Ultra Stretch infrared (IR) upper interior to maximize performance, and All Channel Flex 2.0 exterior to create the highest-level comfort and performance.