Mounting Ring for CAT 51

Telescope tube rings have to be sized very carefully and perfectly. They only work within an extremely narrow range up to the ring's specified inside diameter. DO NOT PURCHASE rings if your tube is even 1 or 2mm larger than the ring size. They will NOT fit!Measure your own telescope tube very carefully BEFORE purchasing these.Please also do not go off what others may have stated elsewhere online or in our reviews. Manufacturers are known to change specifications between different production runs. Finally, we do not have tube sizes or compatibility information so we will not be able to recommend rings or confirm your choice.