The National Hockey League has released NHL Hardest Shot, a new iPhone app designed to measure the speed of slapshots, challenging aspiring hockey pros to put their strength and power to the test. The app uses a sound and speed measurement system to track the puck and instantly measure the speed for standard 20ft and 40ft shooting distances. Players simply need to choose their distance, ensure that the target is a solid surface and place the phone off to the side between the shooting position and the target. Users can also challenge their friends and post their best results to Facebook and Twitter. The app also provides a video library including an instructional video on how to take the best slapshots and clips of some of the hardest slapshots in the history of the NHL. NHL Hardest Shot is available from the App Store for $2.