This Heavy Duty Right or Left Side folding adapter can be used to thread into any AR15 type female buffer tube threaded hole. It offers a flat mount on the other side with the standard ACE type (2) 10/32 threaded holes to mount an ACE stock, and we also include one of our buffer tube threaded caps to install any Mil Spec/ Comm buffer tube or Blade/Brace type buffer tube. Our Upgraded folding adapter offers upgraded machined parts, upgraded stiffer Nickle plated hinge spring, improved, wiggle free locking hinge, locks open and closed, and harder coating. Does not work with standard AR receivers at this time, folding hinge is too large and will not clear an AR charging handle. Weighs about 5.5 ounces, adds about 1".