Brownells now offers AR-15/M16 enthusiasts a new modular flattop riser mount system for Picatinny cut receivers. The customizable mount offers three heights of straight risers and three MOA risers for long range shooting so the shooter can precisely match the scope height and angle to shooting conditions. The system's angled riser mounts provide built-in elevation, preserving the scope's internal elevation range. In addition, the entire unit can be removed quickly in order to use the rifle's factory sights. The system also provides a high degree of sight repeatability when it's re-installed on the rifle.