Forward Controls Design Picatinny Rail Cover Black 6.43in RCP 6.42. Forward Controls Design uses the dimpled surface on applications where it makes sense: bolt catches magazine release buttons. The AA or dimpled surface is the idea of cross hatching same end but different means. Briefly the AA (all angles) surface offers equal traction and friction regardless of the angle of approach i.e. the angle at which the hand holds it or the angle of the finger that presses the control. Serrations can be very effective as long as the movement they're tasked to reduce / mitigate is perpendicular or 90 degrees to the serrations serrations start to lose their effectiveness when the angle of approach is 45 degrees or greater. Cross hatching has no such limitations neither does the AA surface. RCP's locking method is squarely based on Tangodown's SCAR panels. The large dimples pattern isn't new before we started using it and coining the AA description. The spacing between each dimple the size of the dimple as well as the depth all matter Forward Controls Design had the pattern that offers the most tracking and grip dialed in back in 2016 it's never changed since. Specifications for Forward Controls Design Picatinny Rail Cover: Manufacturer: Forward Controls Design Color: Black Package Contents: Forward Controls Design Picatinny Rail Cover Forward Controls Design RCP 6.42: Picatinny Rail Cover Black 6.43in