pre cat lambda sensor?

[Slick S3]

Does the pre catalyst lambda sensor have 4 wires or 6? as i have a freind who is able to get me an NGK lambda sensor, he said it is the correct item for my car and has 4 wires running into the plug....

I checked on the NGK website and they seem to only do 1 for the post cat sensor ( after the cat) so i'm a bit confused and wonder should i get it or not!

Any help would be much appeciated.