SanDisk's Extreme Pro microSDHC cards are the fastest memory cards you can get for your smartphone or tablet. They're also much more expensive than other memory cards, selling for about $60 for an 8GB version and $100 for a 16GB version. And most current phones or tablets aren't designed to take advantage of the extra speed offered by the cards, so if you were hoping they'd help you, say, reduce shot-to-shot time for your phone's camera, or cut the time it takes to open a video on your tablet, you're likely to be disappointed. If you have a device that can take advantage of these cards, they're worth considering. Otherwise, you can just add a good 32GB microSD card to your mobile device for under $20.