These classic front ramps are CNC machined from bar stock steel and hot blued. The dovetail cut is the industry standard .375" (3/8") and the width of the ramp is .340", which is a perfect match for Marble's "MR" series Contour Front Sights, may not function with other brands. Top surfaces are serrated to eliminate accuracy robbing light reflections. Easily installed with a single heavy duty 6 x 48 screw (included).