iBike Dash CC Cycling Computer for iPhone 3G/3GS/4 and iPod Touch Rugged Phone Booth TM case completely encloses your iPhone 4 for superior rain and shock protection Large, full-color, easy-to-read backlit screen Memory size: uses iPhone/iPod Touch internal memory for essentially unlimited ride file lengths and numbers of ride files Windows System Requirements: Windows XP/Vista/Windows 7, Macintosh System Requirements: Intel Mac running OSX 10.5+ Continuous operation can be extended beyond 5 hours by changing spare battery during ride