The Kowa Prominar TSN-EX16 Spotting Scope Magnification Extender increases the TE-11WZ II eyepiece's zoom range by 1.6X. It delivers superb optical performance at even the highest of magnifications, and it's an excellent spotting scope accessory for long-range observation and digiscoping. Plus, it can be used for both terrestrial and astronomical subjects! Easily mounts to the Kowa TSN-99, TSN-88, TSN-77, and TSN-66 spotting scope series. Increases TE-11WZ eyepiece's zoom range by 1.6X Superb optical performance at even high magnifications Great for long-range observation and digiscoping Can be used on both terrestrial and astronomical subjects Compatible with Kowa TSN-99, TSN-88, TSN-77, and TSN-66 spotting scopes