You don't really make clear what you need it for and why you need it. That makes it difficult, if not impossible, to give a sensible advice.
My Apple friend SQUEALED with delight when I showed them my 32GB USB micro drive. I put a 32GB microSD card into this -> http://ecx.images-amazon.com/images/I/41v%2Br9RhHmL._SL500_SS100_.jpg
It's compatible with their Apple Intel Mac Pro.