Holds 2 cards for super large capacity: Get maximum storage capacity with 2 microSDHC or 2 microSD cards. CR-5400 converts 2 microSD(HC) cards into one MS Pro Duo stick. Card types can be mixed: Cards of different capacity and different type can be used concurrently (i.e. microSD+microSDHC). Freedom of expansion and upgrade: The adapter works with only one microSDHC card as well. The second slot can be equipped anytime later. You can exchange the cards and upgrade the max. capacity at will. Super high read/write speeds of 10MB/s and up: CR-5400 is made of high quality components and preserves the original speed of the inserted microsd(HC) cards(when two different types of microSD(HC) cards are used, the slower card sets the speed rate).