Bitsafe needs a device of at least 4 gb with decent write speed. To check for USB sticks speed go to http://usbflashspeed.com/ and aim for device with at least 10 MB/s of *write* speed, the more the better. If you own one of these, you should be ok: Lexar JumpDrive Lightning II Transcend JetFlash OCZ Rally2 Turbo Corsair Voyager GT (rugged!) Silicon Power LuxMini 920 Sandisk Cruzer Contour For SD cards, you should aim for a Class 6 (40x) at very least, better a Class 10 (66x). Raccomanded size: Bitsafe uses about 250MB for binary and 3.5 GB for persistent storage, so you'll need a 4 GB key. Anything over is just wasted. TL;DR: Look for the fastest 4GB drive you can afford to buy.