The Hollis F2 fins are made from a high grade, heavy duty monoprene but are designed to reduce overall weight and size. The double layer blade design increases the surface area of the blade to provide the power and efficiency of bigger and longer blades yet allows easy packing and travelling thanks to the shorter blade length. Vents in the lower blade help to reduce stress on the foot and ankle but also act to accelerate water over the blade. The F2 is fitted with an adjustable spring strap as standard. The strap can be moved between two mounting points on either side of the fin to shorten or lengthen the strap to suit your foot size. The strap has a large thumb loop to aid donning and removal.