Being a Secure Digital (SD) card, the device is about the size of a postage stamp and much thinner than a USB plug (about 2 mm).
I carry the SD card in my mobile phone, which has a SD socket. Alternatively it would fit easily in a wallet. The card comes with a small soft plastic carry case and a hard plastic keyfob (like a memory stick).
What would be more useful is a credit card sized carry case. This could hold four SD cards, slip in a wallet and hold 8 GB. Such cases exist as third party products (holding as many as eight SD cards), but are not cheap and a bit bulkier than they need be:
This memory card wallet consists of a stiff plastic outer shell that is stuffed with thick, heavy rubber holders. The case is heavier than it looks and weighs a couple of ounces. It will support a lot of weight on it without damaging the cards. ...
From: SD Secure Digital Memory Card Storage Wallet, DMSPSD8 , HAKUBA USA INC, Amazon.com