Some customers contact us Said smartphone does not recognize the U disk,then ask Refund,beacause very few models smartphone wiht OTG / micro usb/ external memory device Function turn OFF,please set your phone external memory OTG turn on Set Exernal memory turn on setting>> other setting >> OTG connection but some models is not this name, may be call "micro usb"or "external removeabble memory" if you can not find it, please contact your phone company service center Solutionand 1. If USB flash drive does not work, thenplease try again on other computer / and other Smart Phone 2. Very few smart phone models or Old OS systemversion do not support External storagedevice. If it on other smart phone work well, then please contact your smartphone manufacturer to get help. 3. Does your phone support external storage Higherthan 8GB or 16GB capacity? if it is not supported, please contact us to applyfor a new free 8GB/16GB to testing and evaluating. 4. If USB flash drive does not work on many device. Please contact us get new one, We will solve problem to make you have acomfortable experience.  Operational Guidelines For IPhone mobile :Plug the lightning connector slightly to connect to iPhone, Automatically prompt App(i-Easy Drive) installation at first connect.Also can download on the app store. For Android:There is no need to install an APP for Android phones,Plug the connector slightly to connect to mobile,  the “USB Drive” will be appeared after you touch the screen and slide down from the top of the interface, then you can review the data in the USB drive.  For the computer:plug it in the USB port on a computer and it works.