Peugeot / Citroen BSI unit's

Hi
Some facts you need to know before you bid on a Peugeot / Citroen BSI unit from okay.
These units can only be coded ONCE to the original vehicle it was fitted to at the factory, once an attempt is made at coding a BSI that's it, you don't get a second chance! second hand BSI units are total useless on there own.
For a second hand BSI to work you also need the matching transponder immobiliser keys