Piggyback mounting a refractor on a C11 CGE

Yet another question....

for a scope like the megrez 90 (90mm outer tube diameter, I believe!), what would the most suitable Losamandy Guide Scope rings to get? The 108mm, 125mm or even larger?

Thanks in advance

Yet another question....

for a scope like the megrez 90 (90mm outer tube diameter, I believe!), what would the most suitable Losamandy Guide Scope rings to get?

5" rings will be fine

Yet another question....

for a scope like the megrez 90 (90mm outer tube diameter, I believe!), what would the most suitable Losamandy Guide Scope rings to get? The 108mm, 125mm or even larger?

Thanks in advance

Steve, Measure twice and buy once!! Seriously, I doubt if the outer diameter of a 90mm refractor is actually 90mm, i suspect it is bigger that that.