Saiga 12GA Quad Rail System by TacFire

Solid aircraft aluminum alloy construction with precise CNC machining
Top/middle/bottom 3-piece innovative design allowing flexible accessory applications
Includes 20 left/right/bottom slots and 31 top slots
Designed with see-through feature for use with iron sights
Great zero retention capability for all accessories installed on the rails
Easy installation with no modification to the barrel
Made in China

Here are the specs