I have a new, never used, Mark Brown CQB A3 mount to sell. It is a new one that fits ARMS throw levers. It has never been on an upper. I got it and put one of my ARMS 22 rings on it to make sure they fit, and that was it. Before I got the upper built to use it I got an ARMS SIR to use instead. $145 shipped, or trade for a new black small hole A3 flat-top receiver, plus or minus as needed depending on what you have.