This is the SnowEx D5716 VMaxx Command Console Spreader Control.
A replacement for controller D6835, this controller allows you to make adjustments to the flow rate of your spreading material, the spreading pattern and has an on/off switch for the vibrator.
It measures 7" x 7" x 2" and weighs approximately 3 lbs.
This control works with both V-Maxx in-bed spreaders and dump boxes including: SP-8500, SP-8550, SP-9300, SP-9500, SP-2200 and SP-2400.