The PING Cradle, when used with the FREE iPING Putter App, turns your iPhone 4 or iPod touch into a personal putting coach. Developed by PING's engineers for all skill levels, the iPING Putter App calculates and tracks your Putting Handicap (PHcp) to help improve your putting. All you need is the PING Cradle and an iPhone 4 or iPod touch (4th Gen) – the App is FREE. It is wireless, so you can use it anywhere. Practice and improve at your favorite golf course, at home or on the road. Every session provides immediate results – leading to more consistency in your stroke.