"Now overstable discs are those that are not really meant for beginners. These discs, normally in the driver category because of the design of the disc, require a lot of speed in order to fly straight during flight. That means you need to have a lot of arm strength and power behind your throw. Overstable discs usually fade into the opposite direction of the disc’s spin. So for a rhbh thrower, the disc will spin right and turn to the left. But these discs are usually the most predictable for better players, which is why pros love them so much.
These discs work well in a variety of situations including: serious headwind, skip shots, and for when you need a disc that finishes hard left."