The patented Roller Cam Pin is another example of how far POF-USA will go to reduce friction and drag. Standard AR cam pins feature a square head that grinds along the inside of the aluminum receiver. The nickel-plated roller, on POF-USA's cam pin, smoothly rolls along the receiver without gouging the receiver. As a result, you will never worry about cam slot wear again. Note: The AR-10 version is made for use with most AR-10/SR-25 type bolt carrier groups including the P-308 bolt carrier group.