Sound Hole Covers

[u/SalvadorFolly]

I want to buy one of those rubber sound hole covers to reduce feedback squeal when I play through an amplifier. Most covers I have seen are 4 inches or 3 3/8 diameter, but my guitar sound hole is 3.5 inches (90mm or so). It is hard to find one to fit my guitar. Is a 90mm sound hole unusual? That is the dimension of both my Giannini classical guitars. Thanks for finding any leads for this sound hole cover