This is a much-improved product in our Astro T-2-System portfolio of telescope essentials. This changer-combo works similar to the older T-2 Changing System #2456321, but it is suitable for extremely heavy-duty accessories. The difference between both systems is part-no.6 (included in #2456321) versus part-no.6A (included in #2456322). The (TQC #6A) T-Quick Changer (with Zeiss pressure block) literally equals the Zeiss-original - only it does incorporate a contemporary T-2 female thread (M42x0.75) instead of the Zeiss thread of M44. We are glad that this T-2 clamping/rotating system now is fit for the next 25 years. It will fasten almost any load with utmost security.