For safety against malware, I always first format (FAT32) a drive. Initially, both of these cards appeared to 'hang-up', but secondary attempts successfully formatted. Saw a few negative reviews based on device compatibility, but I tested (h2testw) fine on both Lenovo ThinkPad (Win10) and BeeLink GS-1 (Android 7.1): read 24GB/s write 16GB/s.