List<string> passed in ViewBag gets with “System.Collections

public ActionResult Select(bool isChecked, String id)

 { 

var selectList = (List<String>)HttpContext.Session["SelectList"] ?? new List<String>(); 

if (isChecked && !selectList.Contains(id))

 {               

  selectList.Add(id); } else if (!isChecked && selectList.Contains(id)) 

{                 

selectList.RemoveAll(s => s == id);

 } 

ViewBag.selectList = selectList; 

return Content("OK"); }

public ActionResult AddSitesToUser(string returnUrl,string selectList, int userId = 0) 

{ 

ViewBag.selectList = selectList;

 }

(Html.BeginForm("AddSitesToUser", "User", new { returnUrl = ViewBag.returnUrl,selectList=((List)ViewBag.selectList )})

In my FirstController.cs the list of ViewBag.selectList = selectList; created properly, but if i pass those list of strings to SecondController.cs instead of returning list of strings it gives me '"System.Collections.Generic.List1[System.String]"

Any idea on what I'm doing wrong?

Thanks