The Killa Hydro is a flat swimming goggle that is very lightweight and offers a perfect fit. It is the best choice for swimmers who want small, comfortable swimming goggles. Optimal fit. The ergonomic three-dimensional seal adapts to your face and reduces pressure around the eyes to improve waterproofing. Comfort: The adjustable clip-on straps are very light and comfortable, ideal for intense swimming training. Anti-fog The unique, durable anti-fog coating prevents fogging and always ensures clear vision.