Michael, you will simply need this rail : amazon.com/Monstrum-Tactical-Mossberg-Shotgun-Picatinny/dp/B00ME8SZFS ----------------- It will fit on top of the Laser Saddle and look like this : -- crimsontrace.com/products/laser-sights/ls-250g-lasersaddle-green-laser-sight-for-mossberg-12-20-gauge-shotguns/01-7820.html

Hi,
The four screws (for top part of receiver when installing laser saddle) provided are long enough to accommodate a rail section for optics as well. Most Mossberg 500/590 Series Shotgun (if you are using this shotgun) Picatinny Rail should fit. I hope this helps.