The Williams FRONT SIGHT RISER BLOCK .340 (M) these risers add to the height of the dovetail. Especially handy on models that require higher than normal front sight. Available in two widths: .250" model is for Williams Streamlined ramps. .340" wide model is for all standard ramps. Technical Information Material: Strong, lightweight alloy with a tensile strength of 85,000 pounds Finish: Rustproof, anodized blue-black finish Features: Designed to add .25" to the height of a dovetail front sight Gunsmithing Required: Notes: Comes with an allen wrench to tighten block into place Fits: Williams streamlined ramps or ramps with a 1/4" top width Incorporates a standard 3/8" dovetail