The FN/FAL Recoil Buffer fits in the rear of the upper receiver, preventing the bolt carrier from impacting the lower receiver. The Recoil Buffer fits in all Standard and Para rifle configurations, both metric and inch pattern. Installation takes less than a minute and can be done without any tools. It's that easy. Look at the lower receiver of any FN/FAL that has been shot just a few time. You will see an outline of the bolt carrier, where it has impacted the receiver. When you install a FN/FAL Recoil Buffer™ you will eliminate any contact of the bolt carrier with the lower receiver. With the FN/FAL Recoil Buffer™ installed you'll have less felt recoil, more muzzle stability, less action noise, and extend the service of your weapon, not to mention the peace of mind that comes from protecting your investment while you're enjoying it.