Spark ST Whammy Bars replacement heel supports
They are designed for Arc ST and Surge ST bindings, including their PRO versions. They differ from classic Whammy Bars by the ST technology used, i.e. Smooth Touring, which uses special mixtures of thermoplastic and so-called remelting. Manipulation of the heel support is thus smooth as butter, because the thermoplastic reduces the friction between the components and also extends their service life.