In addition to the high transfer speeds, the cards are UHS Video Speed Class 30 (V30) compliant, allowing smooth, uninterrupted 4K video recording. For everyday moments, capture that moment by selecting the right memory card for your camera. Transcend's SDXC/SDHC 300S memory cards feature high capacity, excellent performance and are ideal for keeping the small moments of everyday life in mind forever. Convincing PerformanceTranscend's SDXC/SDHC 300S memory cards deliver read/write speeds of up to 95MB/second and up to 95MB/second respectively. 45MB/s both the UHS Speed Class 3 (U3) and the UHS Video Speed Class 30 (V30) standards for 4K Ultra HD video recording. Extremely ruggedIn order to offer you the best performance and stability, Transcend's memory cards are tested under the following extreme conditions. -Water: meet JIS IPX7 standards and are waterproof to 1m depth for up to 30 minutes of temperature: withstand extreme temperatures from -25° to 85°C. -Electrostatics: meet EMC IEC61000-4-2 standards and withstand static electricity X-rays: meet ISO7816-1 standards and are also resistant to X-rays during airport control Physical stress: shock and vibration resistant and resistant to bending and turning. Characteristics:-Capacity: 256 GB-3D NAND Flash speed classes: UHS-I U3, UHS-I U1, Class 10, V30 read speed: max. 95 MB/s write speed: max. 45 MB/s-JIS IPX7: waterproof up to 1m depth for up to 30 minutes - Complies with EMC IEC61000-4-2 standard X-ray resistance: ISO7816-1.