My brother has brought some nd filters and when they have arrived they don't fit. They are too big now he has reported back to seller and he says that the filters are for p3 pro and advance or p4 pro. My brother has a p4. Is there any difference in camera lens cover diameter size with the p4 and p4 pro?

yes, the P4 pro filters are larger and will not fit the P4 !

My 3P ND's fits my P4 (not pro).  

Håkan K Posted at 2017-2-5 08:15
My 3P ND's fits my P4 (not pro).

What p3 do you have as the guy said it fits the p3 advance and pro

I have a P3P and a P4. I tried one of my ND that was purchased for the P3P on my P4. It was not as a snug fit as on my P3P but it works.