UHS is a new ultra high speed bus (data transfer connection) for SD memory cards. There are two versions: UHS-I and a more advanced UHS-II type. This refers to the physical construction of the card and does not directly indicate its speed. There are speed standards for UHS cards: UHS 1 guarantees a minimum speed of 10MB/s, which is suitable for full HD video recording, and UHS 3 guarantees a minimum transfer speed of 30MB/s, which is what you’d need for 4K video.