Amusing!!! You can see the charging Speed!!! 2-In-1 Features: sync & Charging. Allows you to charge and sync your device at the same time. Lets you transfer music and data files to and from your device at high-speed transfer rate. One end plugs into your device directly or through a dock while the other plugs into your computer USB port. Flashing blue LED tells you charging status. Built-in Electroluminescent Light (EL) technology lowers power consumption and saves energy. Automatically stops charging your device when fully charged.

Flashing Blue USB Cable For iPhone 4