The Yankee Hill Half Inch Risers meet mil. speck 1913 and use a large screw for more clamping power. Strong and sturdy! They fit any picatinny rail. Great for elevating scopes, sights, flashlights, and more. These risers elevate your accessories 1/2 inch. TheHalf Inch Risers are made from aircraft quality aluminum and hardcoated to Mil. Specs. 3/4 inches long.