The footpad for self balancing hoverboards does a similar job to what a handlebar grip does for a regular scooter. No matter the brand or model, every hoverboard uses two of these footpads, one per side.
The textured surface is what provide's the "grip" for your feet, as well as covering the actuator pads. If your footpad looks like the one in the above photo, then this is the one you need.