our company is a manufacturer of LED displays.We have been in this field for several years.Now,we have invented a new control system called SD card system.You can't connect the displays or screens to your computers with a SD card.You justneed to save the info in the SD ,and put it into the displays,then it is OK with power.Our products are widely used in many fields ,such as taxi LED displays,bus LED displays,LED sreens etc.