The Swarovski FRR (Forehead Rest Range) provides a stable three-point support, so hand-held glassing is more productive and steady. The forehead rest can be adjusted so that your eyes line up perfectly with the ocular eye-relief. It mounts seamlessly on the focusing wheel and replaces the battery cover. The FRR is great for eyeglass wearers as it transfers pressure away from the eyeglasses and eliminates the discomfort of the nose pads digging in and keeps eyeglasses from pressing into the eyelids. The FRR and FRP for the Swarovski NL Pure are not interchangeable.