This is a replacement bolt extension that comes in the package with our Gen 3 ARH300 Folding Stock Adapters.
These are built to fit a standard .625 BCG opening. Fits AR15’s and most AR9’s.
To ensure proper fitment of your AR9, please measure the opening to your BCG. If you find you need a smaller bolt extension we have a .531 available here.
If you have any questions please contact us before ordering.