Yes it is! I ordered the part anyway out of frustration with other suppliers. It just came in. It fits my AR10 DPMS lower in .308 perfectly, better than the magazine catch that was furnished with the "AR10 Lower Kit," that I purchased. When installed, the stud is flush with the outside of the retaining nut, as it is on an AR15. (The retaining nut, or button, is the extended version, used when the stud is too short.)