Designed specifically for use with their Digiscoping VPA Variable Phone Adapter, this Swarovski Optik VPA AR-S Adapter Ring simply screws onto the VPA and is used to mount it onto your ATS & STS spotting scopes. The ring push-fits onto the optic's eyecups and optically centers your phone's camera lens in the eyepiece. This is the eyecup ring only—the VPA smartphone adapter is required for proper use.