UTG 3/8″ to Weaver Adaptor 

• Adapts Most Picatinny Rings and Mounts to Flat Dovetail Rail Interface
• Spring-loaded Adjustable Dovetail Width from 9mm to 11mm
• Removable and Threaded Vertical Stop Pin Provides Added Retention for Dovetail Rails Equipped with Stop Pin Holes
• Lightweight Aluminum and Steel Construction
• Includes Two Adaptors