Mens Shoe Size Small (4 -6) MS (6-7) Medium (7-9) ML (9-11) Large (11-13) Womens Shoe Size S - 5.5 -7.5 MS - 7.5-8.5 M - 8.5-11 ML - 11-13 L - 13-15 The new Delta Viper fins are an asymmetric fin ideally suited for bodyboarding. Besides having a strong powerful kick to get into waves, once on the waves these fins are very fast, creating a minimal amount of drag yet the subtle yellow points create a directed release point for water flow allowing for great control. These control points combine with a stiffer inner rail color which acts as an extension of your big toe further enhancing control while riding. All VIPERs are high performance surfing fins for the intermediate to advanced bodyboarder or bodysurfer. All MS VIPER surfing fins are made of superior natural rubber compounds. All MS VIPER surfing fins float high and are visible in the roughest surf conditions.