Rcd 310 aux output question

[gaz b]

Hi chaps,
              I have an rcd 310 in my transporter and would like to play music from my mp3 player which has a 3.5mm jack.

If I bought this cable from eBay would it just be plug and play or do I need an mdi?

Any advice greatly recieved! 

http://www.ebay.co.uk/itm/Aux-adapter-car-radio-for-iPod-MP3-Player-for-VW-RCD210-RCD310-/380461854623?pt=UK_MP3_Player_Accessories_Cables_Adapters&hash=item58954b2f9f#ht_1161wt_947