See what ive seen on the internet says they are 6 1/2 and some shops have told me they are 5 1/4. I still have the stocks and pulled them out of the closet to look at them. The cone area is 5 1/4. The whole thing is a little smaller than 6 1/2. If i take the plastic ring out mounting depth very minimial. Found some ads off of ebay for about 250 or so. but its ebay... Don't think i want another set of polks.