How To Pass values One webpage to another webpage

SourcePage:-

 protected void btnCheckOut_Click(object sender, EventArgs e)
    {
        string PriceTotal = Txtsum.Text.Trim
            ();
        Session["PriceTotal"] = PriceTotal;
        string TotalItems = TextBox1.Text.Trim();
        Session["TotalItems"] = TotalItems;
        Response.Redirect("paymentgateway/pay.aspx");
}


Destination Page:-

 protected void Page_Load(object sender, EventArgs e)
    {
        TextBox1.Text = Session["PriceTotal"].ToString();
        TextBox2.Text = Session["TotalItems"].ToString();
     
    }