Picatinny Weaver RIS 20mm Standard adapter Rail Mount Base Features: Constructed by high quality of metal material 20mm Standard Weaver Base Rail Easy to hook up， install in seconds All necessary nuts are included All Matt Black finish & Construct of Alloy Metal Note: the little wrench has two colors: black and silver， and will be sent out at random. Specifications: Weight: 31g Length: 115mm Rail Type: 20mm Standard Weaver Rail Built Material: Metal Color: Matte Black The distance between 2 holes is 1.5CM