The "PC" end of a USB 3.0 cable will fit into a USB 2.0 port. This gives backward compatibility. Consequently, if only connecting to USB 2, then either direct connection or a male/female extension should work fine.
The USB 3
disk end (assuming my tosh is industry-standard, and not some wretched proprietary connection. I hope that's a safe assumption to make) is very different to USB 2 mini or micro. It is as wide as the PC end, but only half the hight. It is divided into two parts, and could be said to look like an "m." No USB 2 cable would fit it.
Err, worth a thousand words...
View attachment 7259
(Sorry, the Defy+ is a nice phone with a lousy camera. The it's-USB-
3 give-away on the left-hand plug is that the plastic insert is
blue.)
I need USB3 to USB3, as I am connecting to a USB 3 port on the PC, so a USB 2 extension won't do.
Then USB 2 extension cable as mentioned should be good for you. If you can get one, a USB 3 extension would be "future-proof".
At least for the USB-2 extension, your local electronics or computer shop should oblige. I have even put one on Wife's shopping list, and yes, she came back with the right thing.