Tech 2 Swim Fins - Size Medium Sizing - S(men: 6-7,) M(men: 8-9), ML(men:9-10), L(men: 10-11), XL(men: 12-14) Patented V Rail for increased kick to trust ratio and traction. Powertude drainage system. The principal function of the HYDRO TECH 2 SWIM Fins is to enable anyone from a novice to an Olympic standard swimmer to achieve an exact balanced kick, while using their preferred armstroke. As well as strengthening and toning the muscles, using the fins during swim training gives the legs neuro-musclular memory so that when the swimmer then swims without fins, they kick more effectively. Color Shipped May Vary. Black, Blue Ice, or Ice (clear).