Check the listing for details. Celestron 8" W/ Hyperstar Tri-Bahtinov Mask, Hinged Design!. Condition: New. Listed at 17.09 USD. Celestron 8" W/ Starzona Hyperstar Tri Bahtinov Mask, Hinged With 89mm I.D. Bolts together. One as a pivot and other end bolts to stay shut once on telescope. Now upgraded and thicker mask to have more strength. Version Three of original hinged Celestron HD 8 Inch , this version us a Tri Bahtinov has 89mm inner diameter so it will fit all types of Celestron 8 inch models. check specifications and measurements before purchasing for your telescope. . This is meant for Celestron 8 inch with Starzona Hyperstar. And the regular version , if buying for regular version it may have some space in middle diameter hole and that is so it fits all versions. Special design to split apart and has bolt and nut hinge to pivot on your 8" telescope without taking off parts from Starzona Hyperstar . Comes with set of 1 bolts and nuts and Bahtinov mask. Can put on and off even easier. More options will be available for the HD 8 hopefully soon. Tri Bahtinov Focus Mask for Telescope - Celestron Edge HD 8" or any Celestron C8, Celestron 8 inch.Condition is New. Shipped with USPS First Class. Software Designed and tested. Works great with these and similar models. 3d printed and designed by Spencer 3d. As always fast USPS SHIPPING. 2 TO 3 DAY SHIPPING. BLACK . Other colors and types available just ask. Fits Celestron HD 8 Inch. If need a particular size message me,or if have questions.