Description Dawson Precision Optic (DPO) System for Holosun 509T, Tactical Height, Black Co-Witness Rear Sight. This is a Great Tactical option for Hard Use tactical environments. Patented Dawson Precision® Optic (DPO) Tactical Reflex System for Holosun 509T Reflex Sights. Fits all Staccato DPO equipped pistols, will not fit other cuts. Requires Tactical front sight. Holosun Adapter Plate with .385″ Tall x .135″ Notch Black Co-Witness Rear Sight Installed Tools and Hardware Included. *Note: This item is Not Eligible for discounts or dealer pricing.