Agena 1.25" Wireless Illuminated Reticle Eyepiece with Focusable Crosshair - 12.5mm High quality 12.5mm focal length Plossl eyepiece with red LED-illuminated double-line crosshair reticle Excellent for accurate polar and go-to alignment, and for centering guide stars for astrophotography Adjustable image and reticle focus and adjustable reticle brightness Bright high-contrast views with a 40 apparent field of view and 5 mm eye relief Illuminator equires SR-54 / LR-44 batteries (included)