RJ Firearms from McMinville is where the muzzle break came from... Standard 1/2x28 threads. Don't own an AR anymore or anything I would use it on. No crush washer. Believe it or not, this break works very well for reducing muzzle rise. I could get some of the quickest follow up shots (100y) with this vs the standard birdcage. 1" Leupold rings. They are .500" high. Measured from bottom of ring, to bottom of base. Pulled from rifle when I upgraded from a 1" scope to a 30mm scope. $25 each or buy both for $40 Shipping is available. $45 shipped for both to your door or place of employment so your wife doesn't find you keep spending money on an AR.