Look for the U3 icon - This indicates a high-speed card. U1 cards are standard speed. Ideal for Mobile Phones, Tablets and Valve Steam Deck Look for the read and write speed. Standard cards only indicate the transfer speed (read). buy a premium high-speed Memory card at a standard price Premium high-speed performance: up to 100MB/s read speed and up to 50MB/s write speed High temperature resistance, water resistant, Shock proof and X-ray proof