Only work on air guns

First you have the Picatinny 20mm rail pistol

Material: High Quality Plastic

Rail Type: 7/8" 20mm Picatinny/Weaver

Quad rail: Upper rail with 7 slots ,other rail with 3 slots

Finish: Matte black Finish

Net Weight: 54g

Specifications for the Pistol:

Installation and: Picatinny

Compatible pistol Thickness: ≤28mm (1.1 inches)

Compatible pistol height: ≤43mm (1.69 inches) 

External specification：

Mount length:12cm（4.7 inches）

upper rail length:8cm（3.1 inches）

side rail length:4cm （1.57 inches）

down rail length:3.5cm （1.37 inches）

Fits for： s&w/1911/Glocks series/Walther p22/HKp30/SD9VE 9mm etc