I've been working for Mercedes Benz for 8 years now. Under no circumstance can a dealer reprogram a key to be used for your vehicle. Once a key leaves the factory, it is permanently imbedded with the code for that vehicles' VIN, and all its optional features such as keyless go.

Purchasing a Smart Key on here, whether it be switchblade style or not is useless. You will never get that key to work for your vehicle.

Our dealership alone gets about 5 people a week stating that they bought a remote key from ebay, and need it to be recoded/reprogrammed for their car. It can't be done, and out the door walks another person who tried to save a few bucks, and is now out all that money.

It does not matter that they advertise that it's for keyless go, or it has never been programmed for any vehicle. That isn't true. Mercedes Benz will never send out a key without it being coded. To get a replacement key for any vehicle you have to show your proof of ownership (title), proof of insurance, and driver license. Don't believe their lies. It cannot be done.
 I've seen people selling some of their "extra keys" on here as well. Don't do it! Just because you didn't really need that 3rd key, and you'd like to help someone out with a key for cheap, just don't. It cannot be reprogrammed, and also, it's easy for them (the purchaser) to see your return address when it arrives, go to your house, and take your car.

I don't know about other manufacturers keys, but I know that Mercedes Benz keys are this secure.

Please, just get your keys from your dealership. Don't lose money trying to get one on here.