Kowa TE-10Z 20-60x Zoom Eyepiece for Kowa TSN-880 and TSN-770 Series Spotting Scopes Optional eyepiece designed to be used with your Kowa TSN-880 or TSN-770 series spotting scope 20x to 60x magnification zoom eyepiece that provides with a range from 115-55 feet at 1,000 yards Easy to install, requiring you to simply push in the eyepiece, and then pull it out again for detachment Features an eyepiece locking mechanism that prevents it from getting lost or falling out Interchangeable eyepiece has an eye relief of 17 to 16.5 millimeters