Ordered from Wilson Combat for my PC II in 9mm. I wasn't sure it would fit but it does...comes with a 1/4" guide Rod which is a little smaller dia. and about 5/16" shorter, it's end cap has same diameter hole that matches the rods dia. The rod is set back from the end cap about 5/16ths.looking inside from the front. It allows disassembly n back without the tool.The 15# flat recoil spring is sized to fit on 1/4" guide rod...this spring won't fit on stock factory guide rod. The tension racking the slide now is the same as before but flat spring has a longer life span into the thousands per there data....