A high-speed bus interface
“UHS” stands for “Ultra High Speed” ― UHS has a high-speed bus interface that achieves high-speed data transfer performance. Theoretically, UHS-I standardizes data transfer up to 104 MB/s. The high speed of UHS-I can only be achieved by combining a UHS-I compatible memory card and a UHS-I compatible device. It works with non-UHS-I devices, but the performance is different than the performance with a UHS-I interface.
For more information, please refer to the official website of the SD Association: