A device for spreading a granular material over a road surface. The device includes a hopper fillable with the granular material and an agitating member configured to discharge the granular material from an outlet of the hopper. A brush is aligned with the outlet of the hopper and includes a plurality of bristles configured to inhibit leakage of the granular material from the outlet of the hopper during stoppage of the agitating member. Also provided are a system in which the spreader device is mounted on a vehicle, and a method of operating the spreader device.