My AR-15 has standard A2 rear sights. I constantly worry about them inadvertantly getting turned out of adjustment. I have been even considering going to an A1/C7 upper receiver to prevent that from ever happening. And then I heard about RRA lockable A2 rear sights. How do they work mechanically? Are both the elevation wheel and windage wheels lockable? What parts would I need to order from you in order to convert my standard A2 rear sights to the lockable A2 rear sights? Is the lockable windage knob marked with 8/3 or 6/3 as the lowest setting? Does the lockable rear sight have 1 MOA elevation adjustment and 0.5 MOA windage adjustment? If I shipped you my complete upper half could you install the lockable A2 rear sights for me? What would be the parts cost, installation cost, return shipping cost and turnaround time? And do you happen to know if these lockable rear sights are legal for CMP Service Rifle matches? Thanks.