Description Dawson Precision Optic (DPO) System for for Holosun 507K, Carry Height, Black Rear Co-Witness Rear Sight.. This is a Great low profile system from Every Day Carry! Patented Dawson Precision® Optic (DPO) System for Holosun 507K Fits all Staccato DPO equipped pistols, will not fit other cuts. Requires Carry Height Front Sight. Holosun Adapter Plate with .335″ 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.