The Integral Fusion 3.0 is a capless, small and lightweight leave-in' metal USB 3.0 Flash Drive measuring only 21 x 12 x 4.5 mm, yet offering capacities up to 32 GB.
http://www.notebookcheck.net/Fusion-3-0-packs-up-to-32-GB-in-a-tiny-package.98834.0.html