Are all USB cables alike. No, where the difference is in being 'USB Power Port Ready' or not. For example, many manufactures use special wall chargers where each manufacture has their own special wiring specification inside the wall charger to put their device into proper 'charge mode'. Without this proper wiring yuor the mobile device will not charge using a USB cable. For example a common misunderstood connector used by manufactures are micro & mini USB type connectors. These physically look the same but required different wiring to properly put mobile devices into the proper charge mode. At Gomadic we put this special wiring in the cable hence why title says this retractable USB cable will charger but will not offer USB data transfer. Most people are not using the USB cable for data transfer we decided to convert this product line into a USB charge *only* cable. In the case of the Elonex 621EB eInk eBook Reader you might have gotten away with using a USB data cable in the past but to ensure you don't get stranded when you need a charge most we have integrated the wiring in the connector end that plugs into your Elonex 621EB eInk eBook Reader to ensure no mater what type of USB power port you use your device will charge, Note that all Gomadic products come with a Lifetime Warranty.