Adapter Ring Cokin

Adapter Ring Cokin
What is the difference between P and A Cokin Filters Cokin filters?

I still see Cokin P filters and ring adapters are more expensive than the filters Cokin A and ring adapters. So what really is the difference?

From very small rings (36 mm – to fit rangefinder / camera compact high-end) and a maximum of 62 mm in size of the thread. P rings ranging from 48 mm to 82 mm and covers the critical size of 77 mm lens wearers many pro (is ie, 2 3 lens in Nikon Holy Trinity with filters from the front).