Constant field of view: During the zoom process from 3mm to 8mm, of view of the eyepiece remains constant at 56 degrees, providing users with a completely different experience of using a zoom eyepiece Parfocal design: No need to refocus no matter how the length is changed Constant pupil distance: No need to adjust eye position to adapt to changing pupil distance and changing field stop diameter, improving visual experience Foldable and removable environmentally friendly rubber eyecup and non-slip rubber protective ring. Stainless steel rubber sleeve, supports standard 1.25-inch filter installation Mainly suitable for short ratio mid-to-high-end refracting astronomical telescopes (portable OTA) and large-magnification lunar and planetary observations Colour:Black & Silver Material:Optical glass + stainless steel + rubber Package Contents: 1 * Telescope Eyepiece Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.