This flattener allows is needed when using the 76D flattener on a Takahashi telescope for terrestrial viewing. It adjusts the position of the flattener relative to the focuser draw tube to allow for the telescope to have a closer focus point.
End 1: M56 x 0.75 female thread
End 2: M56 x 0.75 male thread
Metal Back: 17.5 mm
Recommended for the Takahashi SD Ring for 76D Flattener