This 2-inch Visual Back threads onto the rear cell of Celestron 11-inch to 14-inch SCTs with 3.29-inch male threads on the telescope's rear cell. It provides a full 2-inches of unobstructed opening (unlike most visual backs).
Use the AP 2-inch Celestron Large Rear Cell Adapter with 2-inch accessories that slip in, such as a 2-inch diagonal, Barlow, 2-inch eyepiece, or binocular viewer. This visual back features AP's unique brass locking ring design and 3 large thumbscrews to hold your accessories securely and squarely; ideal for critical applications. If you prefer to use just one thumbscrew on occasion (perhaps if you are interchanging light accessories frequently), simply remove the extra 2 thumbscrews for that session.
Note: Celestron EdgeHD scopes have a restricted rear cell that may not allow accessories with a long nosepiece to fully seat in this adapter (the AP Maxbright diagonal will not seat). It is recommended to choose the ADASCTLC27 and ADA2003 (or ADA20132) as an alternative when using the EdgeHD scopes.