This is the SIM 600 - 12 Month contract: 600mins 3000txts 1GB internet. This is £15 a month direct with Three but quidco are giving £81.82 for taking out this contract which means it works out at £8.18 a month which is a bargain!
In my opinion, this is better than the t-mobile deal for 40p extra you get more: 2500txts and 500mb internet.
If link does not work just go to: http://www.three.co.uk/Pay_Monthly/SIM_Only/Choose_your_SIM
and select SIM 600 12 month for more details