Tenebraex Adapter Ring Objective Black for Nightforce ATACR F1 42NFC0-AR acts as a unique and useful piece of device. It assists in the installation or attaching of an array of accessories like ARDs, flip covers or flip caps to the rifle scope. Built in compatibility with Nightforce ATACR F1 scopes, the black Tenebraex 42NFC0-AR adapter ring is to be placed at the objective end of the scope.