bogobble,

Are you referring to the North American Archery Group's version of the perimeter weighted single cam (which I think is up to the PWC2 version if I am not mistaken). The initial PWC cam from "Jennings/Fred Bear,etc.." had a smaller round perimeter weighted lobe, similar to the Mathews' cam, but the PWC2 has a "tear drop" shaped perimeter weight which supposedly increases the attributes/effects of this style of cam.

Or, are you referring to the perimeter weighted style single cam in general? Just about every company uses some form of the perimeter weighted style single cam...with or without the perimeter weight. Mathews was the first to introduce the perimeter weight to a single cam bow but others have followed since then.