Vision Tracking Discs For long throws and fast paced action Flies 200+ Feet Flexible and safe to throw indoors Hitable Catchable Throwable For Baseball, Softball, Hockey. Football and more. Great to work on Small Tracking DIRECTIONS: Hold your Vision Tracking Discs with the domed side facing up and your index finger in the perimeter groove. The throwing motion is most similar to skipping a stone. Allow the Vision Tracking Discs to spin off your index finger upon release. SPECS: DIAMETER 2.5 INCHES HEIGHT 0.5 INCHES WEIGHT 0.7 OUNCES