Williams Gun Sight WDOS Dovetail Open Sight. Lightweight high strength alloy. Steel screws and locks. Fits standard 3/8" dovetail. Anodized black finish. rustproof. the revolutionary design of the WDOS means no more driving or hammering an open sight into the dovetail of the rifle. It simply slides into the dovetail slot in the barrel with finger tip pressure. As you tighten the locking screw it snugs the dovetail on the rifle barrel and locks the sight in place.