I live in an old house and the outlets don't have the third grounding pins. I used to use those cheap adapters you get at hardware stores, but the ground never works on those. I have busted a few too many computer power supplies because of this, so I decided to try this out, and it works well. I screwed and plugged this in, and I tested the other end with a multi-meter and my computer is now properly grounded.
PROS: Low Cost Good Quality Works great when you don't have the third grounding pin Works great whether or not your outlets are polarized It has some sort of built in thing to make sure the hot and the ground are in the right part of the connector
CONS: You have to be careful when screwing in the ground wire, if you over tighten the screw the wire will come off the screw, and you have to start over
one of those for a good price you might as well throw it on your order items.
I occasionally find myself in Precarious Plug situations and I thought this would be handy to have. the quality is really nice apart from the spade connector which could be a stronger metal. pair this up with one of those IEC to nama 5-15 adapters for a handy extension 2 1/2 prong adapter. I already have one that is 6 inches long and lives in my laptop bag ( monoprice has them ) although I will be looking elsewhere for the all-in-one molded version.