Measure accurately - TruGlo Fat Bead Replacement Sight

TruGlo size chart said to use 6-48 thread for an Ithaca barrel. that's what I ordered for an 18" cylinder bore, Ithaca barrel. I removed the old bead sight, opened the package and found the new sight was too big for the hole in the barrel,should have been a 3-56 thread.It was also too long as it would overhang the end of the barrel. So, it now sits in my spare parts box, waiting for the right barrel, but it is very bright.
Pros: Very bright
Cons: extends over end of the barrel,

This review was written in the old system and had content requirements that are different than reviews written today.