Mini Bullet USB Port Car Charger Adaptor for iPhone 4 4G 4S iPod Touch Black
Ebay item number: 170846029882
Unfortunately this item is broken. The spring part that normally contacts the positive terminal inside the car socket does not poke out enough. This is because the spring inside is broken and too short. See photos below.
Note that the spring is too short. The end of it is broken off. This can be seen better in pictures 2 and 3.
Note that the end part covering the spring is too far in. This is because the spring is broken and too short. The end part should be sticking out much further so that it can contact the part inside the car socket.
Here is another view showing the spring. Note that it is broken and too short.