No longer do you have to keep sliding the OTA through the rings to achieve perfect balance.
Different size weights and spindles can be made. All that's needed from the customer is external diameter of of tube rings to match the brackets and size of scope. This example was made for a 5" Istar, so quite a heavey beast and it works a treat.
Or if you want info on how to make it yourself, just let me know I'd only be too pleased to help.