Fisher 86663 and 86664 are individual curb guards for snowplows, with the key difference being their side of installation. The 86663 is the driver-side (DS) curb guard, while the 86664 is the passenger-side (PS) curb guard. These heavy-duty, abrasion-resistant parts are designed to protect the outer edges of the plow blade from damage when plowing along curbs and sidewalks.
 
Pieces are sold indiviually, without hardware; if you need the whole kit, see part number 80297.