When mounting on a square post this bracket is required for PRO1000/1200. PRO1500, PRO2500/2550/ PRO3000/3200, MIGHTY MULE 350, 500/502 AND 700/702.  It allows mounting of the actuator arm on the post side of any flat surface.(The operators come with a mount for a round post connection out of the box. You will need a pair of these adaptors for each operator arm. for a dual swing gate you will need four of them. They are sold individually.