Antenna Mount Bracket is designed to accommodate two way communications antenna. Bolts on existing holes in upright and places antenna atop upright post. This bracket can be used on the driver and or passenger side. 7/8in. hole in 3-1/2in. square base.\nAntenna Mount Bracket; 3.5 in.; Square Base; Comes Pre-Drilled w/7/8 in. Mounting Hole; Backrack ;\nNOTE: If using with Safety Rack, Louvered, Open, LV, TR & SM drilling and cutting is required.\nUniversal Fitment