There's no need to go with a pistol-caliber specific AR lower on your next pistol-caliber carbine build. With the Stern Defense AR-15 9mm Conversion Adapter you have the ability to utilize popular pistol magazines which you may already have a supply of. Stern Defense make two differ models of their Conversion Adapter, one which uses Glock magazines, and one which uses either Smith & Wesson M&P or Sig 320/250 magazines. The Stern Defense AR-15 9mm Conversion Adapter is easily installed into any mil-spec AR-15 lower receiver within seconds and even incorporates a last-round bolt hold open feature. Each adapter is machined from aluminum and requires the use of a 9mm/.40 S&W barrel and a Glock-cut bolt. Made of aircraft grade aluminum Lightweight, ergonomic design Installs in seconds If you’re considering converting your AR-15 to a 9mm, give the Stern Defense Adapter a thought!