Yankee Hill Machine Six Inch Rail Extension 0.5 Inch Riser. Add an extra mounting surface to any picatinny rail and also elevate the mounting surface by 0.5 inches. Made from aircraft quality aluminum and hard coated to mil-specs. Specifications for Yankee Hill Machine Six Inch Rail Extension 0.5 Inch Riser YHM-9473: Mfg Item Num: YHM-9473 Type: SIGHTS/OPTICS - BASES/MOUNTS - AR STYLE AR-15 Parts: AR-15 Parts Desc.: Six Inch Master Model Header: Rail Extension Riser The Yankee Hill Machine Six Inch Rail Extension 0.5 Inch Riser YHM-9473 is a quality addition to the Yankee Hill Machine lineup. For more great deals on Picatinny Rails by Yankee Hill Machine please browse our Yankee Hill Machine Gun Parts page. Yankee Hill Machine Six Inch Rail Extension 0.5 Inch Riser