I don't have one, I have a competitors product the RSA key, which has no USB port at all, you type in the numbers it gives you. Little LCD screen and a buttion. I don't keep mine on any chain, I carry it seperately from anything else.
However, I have to say, for what it is, I have been quite impressed with its durability, in fact, I would say it sets a standard that few devices I have encountered have met, but most all really should....has it ever been through the wash?
My wife has unceremoniously washed, and dried (not hanging dry, in the electric dryer) my RSA key no less than 3 times. Each time it has stopped working properly for a few hours, occasionally displaying gibberish, but it has always started working ust fine again, and usually the visible water drops under the screen go away within a few days.
After the first couple of times I paniced, I have since decided this is in fact the standard of quality we should expect from more devices.