The neoprene jacket offers hard-core protection for your portable music device, while the built-in magnets hold the pouch securely to the fuel tank. The clear play-through window permits touch-screen control and the anti-skid interior allows the pouch to accommodate players of various sizes. The clamshell design makes inserting your player into the pouch quick and easy and the double zipper allows for headphone and output cables to exit the pouch at any point on top, bottom or one side of the pouch. Works well with many MP3 and other personal music players, but should not be used with hard-disk memory players. Window measurement: 2.25" W x 4.0" H.