Sylvan Arms Left Side Folding Adapter - SA5P-L : The SA5 was designed and tested with professionals and protectors in mind. Turn your AR into a compact, concealable platform with a folding stock adapter built to enhance your rifle. Made in the USA, the SA5 is lightweight and 250% stronger than our 4th gen adapter. As with the Gen4 adapter, choose from a left folding or right folding option depending on your needs. Built to work and built to last, the SA5 is user-serviceable and easy to install. Compatibility Details Compatible with .223/5.56, .308, 300 Blackout, and most 9mm ARs. 9mm bolt carriers with standard sizing, 5/8 ID (.625) can use the included bolt extension after removing the pin and weight from the back of the BCG. Does NOT work with Tippmann 22 or LWRC Pistols.