Nikon 64GB XQD memory card, transfer speed 440MB/s, write speed 400MB/s. Used only a couple of times to fill it up on a Z6, so it hasn't been used much. There are no problems. - Brand: Nikon - Model Name: XQD 64GB - Transfer Speed: 440MB/s - Write Speed: 400MB/s - Capacity: 64GB - Included Items: Instruction manual Thank you for looking.