Taken directly from Systema USA's website:
"This is by far the quickest, cheapest, and easiest way to F-Up your cylinder, bar none!! Furthermore, you can install anywhere from just one to all 5 of the precision spacers over your spring guide, which gives you lots of flexibility to F-Up your cylinder to different levels. This allows customization never before possible in the history of PTWs. You can F-Up your PTW however way you want!"
Hee hee....
