i want to show two values in one dropdownlist as length × width like 12 × 6 in mvc4 db first

<div class="editor-label">
            @Html.DisplayName("Length") |
              
        </div>
        <div class="editor-field">
            @Html.DropDownList("Size_ID",ViewBag.Size_ID as SelectList)
            @Html.ValidationMessageFor(model => model.Size_ID)  
            
        </div>
        <div class="editor-label">
            @Html.DisplayName("Width") 
        </div>

        <div class="editor-field">
            @Html.DropDownList("Size_ID",ViewBag.Size_ID2 as SelectList)

        </div>

// GET: /Carpet/Create

      public ActionResult Create()
      {
          ViewBag.Size_ID = new SelectList(db.Sizes, "Size_ID", "Length");
          ViewBag.Size_ID2 = new SelectList(db.Sizes, "Size_ID", "width");
          return View();
      }

      //
      // POST: /Carpet/Create

      [HttpPost]
      public ActionResult Create(Carpet carpet)
      {
          if (ModelState.IsValid)
          {
              db.Carpets.Add(carpet);
              db.SaveChanges();
              return RedirectToAction("Index");
          }

          ViewBag.Size_ID = new SelectList(db.Sizes, "Size_ID", "Length", carpet.Size_ID);
          ViewBag.Size_ID2 = new SelectList(db.Sizes, "Size_ID", "width", carpet.Size_ID);
          return View(carpet);
      }

public ActionResult Create()
      {
          //var sizeList=from s in db.Sizes
          ViewBag.Size_ID = new SelectList(db.Sizes,  "Size_ID", string.Format("{0}X{1}", "Length", "width"));
          //ViewBag.abc = ViewBag.Size_ID;
          return View();
      }