JIAQI see-through Throw Lever Riser Mount Picatinny Riser Mount with 13 Slots Double Rails Quick Release Detachable fits Scope Optics 
 
Product Description:
Machined from Aircraft-grade Aluminum Alloy with Anodized Black Matte Finish.
It provides universal platform that is comaptible with Picatinny and Weaver type standards. The general angle mount of 45 degree is for Installation on standard Picatinny/Weaver Rails.
Its ideal platform provides an additional height for mounting optics with large objective lenses quickly and securely .
Features a see-through channel for using with iron sights.
Friendly Quick Detachable Release Dual Throw Lever Lock riser mount base with full adjustability to fit on standard 20mm Picatinny Rails.  
 
Spec. 
Length: 5.51 inch ( 140 mm )  
Weight: 5.2 ounce  
Height (from top to bottom): 1.02 inch / 26 mm  
Top and offset picatinny rails (13 slots)  
Fits on standard picatinny 20 mm rails