This product is only when adding to Binotron -27 order and sold at near our cost. For ordering alone, choose "Collitron Reticle Only" in the shopping cart. The Collitron Reticle allows The Binotron 27 to be collimated in a minute or less indoors with a pair of eyepieces. Only a well liut room is required. No telescope is needed so you can check and super fine-tune your Binotron alignment if ever you feel it is necessary. A pair of eyepieces (we designed the Coliitron witn our D21 Eyepieces though other brands work also) are all tat is necessary! Keep the power switch arms OUT, point to an evenly illuminated wall and you will view a reticle with grid lines in both the right and left eyepieces. Please see the videos below for more information.