I purchased these as spares when I bought my Z9, but I never had the opportunity to use them, so I'm selling them. I opened the package and tested their operation to confirm they work for this listing, but they have never been used in the field. This is a set of two cards. ProGrade Digital 【CFexpress Type B】 COBALT 1700R - Brand: ProGrade Digital - Model: CFexpress Type B - Capacity: 650GB - Read Speed: 1700MB/s - Write Speed: 1500MB/s