adding attribute in dropdown list items

Hi,

    I have a custom class with three properties Coordinator (string) , userID (int) and ContactId (GUId). I am getting ILIST of this class objects and casting it to Arraylist (Line 1 below).  I want to show coordinator on front end and userID and contactId on backend. how can i do this. Can I add attribute to listitems (Line 4 below)? Should I cast ILIST to something else.

ArrayList CoordinatorsByGroup = (ArrayList)messageController.GetVanpoolCoordinatorsByGroup();

drpGroupNumber.DataTextField = "Coordinator";

 drpGroupNumber.DataValueField = "UserId";

 drpGroupNumber.Attributes.Add("ContactID",CoordinatorsByGroup.ContactID);  // it gives error

drpGroupNumber.DataBind(); drpGroupNumber.Items.Insert(0, new ListItem("Select Group", "0"));

Thanks in advance
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