I'm replacing the plastic thru-hull fittings on my boat while we are painting it and as I was looking them up I noticed they come in 3/4, 1in, 1 1/8, etc.

What is that the measurement of??

How do you measure them??

Is that the size of the hole in the fitting or the size of the hole they fit "thru"????

I'm replacing them with stainless and found them at a pretty reasonable price on E-Bay!!

I'm thinking it is the size of the hose ID that fits on it... So a 3/4 inch thru-hull fitting probably needs a 7/8 inch hole to fit through...