It's quite a few years since I did mine..The black box is the part you need,I can't remember about the wire.It should be obvious if you need the wir when you get the parts.The smaller part is to eliminate the not seat belt fasten noise as when you fit the emulater ,the eco thinks the seat is occupied .
Below the add I have attached are detailed fitting instructions.Hope this helps.
https://www.ebay.co.uk/itm/Passenger-Seat-Occupancy-Mat-Bypass-For-BMW-Z4-Series-E85-Airbag-Sensor-Emulator/161845448155?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160811114145%26meid%3Deb8926d072ea4040b831d9347f5b328b%26pid%3D100667%26rk%3D3%26rkt%3D8%26sd%3D150987109709%26itm%3D161845448155%26pmt%3D1%26noa%3D1%26pg%3D2334524&_trksid=p2334524.c100667.m2042
