Softballs are rated based on two metrics - Coefficient Of Restitution (COR - pronounced like core) and compression. COR represents how "bouncy" the ball is. The higher the COR, the more bouncy the ball is and, generally, the farther it will fly. COR is the percentage of reduction in speed for a ball bouncing off a wall. If a ball is thrown at a wall at 80 miles per hour and bounces off at 40 miles per hour, the speed has been reduced by 50%. The ball would be rated with a COR of .50 (referred to as a fifty COR ball). If your league plays with a .44 COR ball, the speed bouncing off the wall would be 35 miles per hour.