To use the Marker Kingpin bindings with boots that have shallow heel welts, you'll need this adapter. Four screws drill into your boot heel and hold it into place, adding only a few grams and making your lightweight boot compatible with this powerful pin tech/alpine hybrid binding. If you have any questions or are unsure about whether or not your boot requires this adaptor to fit the Kingpin M-Werks, feel free to email or call us and we will do our best to help you sort out what you should do.