Feel easy and move really fast. Viper SL is a more flexible and easier version of Viper and has better respiratory properties. A mesh store has been added on the top to provide maximum breathability and comfort. Viper SL also has a new heavy construction for comfortable fit and to provide the stability needed on the plan. Skoon's bottom has all properties from Viper and the design provides a comfortable, enclosing fit and keeps the foot in the right way.