This extension will help you realize the full imaging potential of your Baader Fluorite Flatfield Converter (BPFFC) or 2" Advanced Convertible Barlow (BARADV). With the internal thread on this extension, you will be able to attach your BPFFC, BARADV, or other accessory with male T-threads INSIDE the 2.7" extension tube. This results in your camera, filter wheel, off-axis guider, or other accessories being fully supported by the much more rigid and robust 2.7" tube system.
Even better, the Barlow only needs to support its own weight inside the extension tube. This proves to be important when imaging at some of the higher magnification factors achievable with the BPFFC, where over 12" of extension may be used between the Barlow optic and the focal plane! The maximum OD of the T-thread accessory that will fit inside this extension is 2.5".
Overall net spacing is 0.75" (19.05mm). However, it has a net spacing distance of 0.9" (22.86mm) for the internal optic.