Transcend Macbook Pro External Desktop (TS256GJDL360), Capacity 256 GB, Flash MLC, Up to Read: 95 MB/s,Up to Write: 60 MB/s, Operating Voltage 2.7 to 3.6 V, Operating Temperature-13 to 185°F (-25 to 85°C), Durability 10,000 Insertion/removal cycles. The 256GB JetDrive Lite 350 Flash Expansion Card from Transcend offers you 256GB of extra storage space. The JetDrive Lite card fits flush in the card reader slot of your MacBook Pro and offers read speeds up to 95 MB/s and write speeds up to 60 MB/s.