Display only .pdf files from a directory

In mu asp.net+vb web there is a page in which i display files from a folder in web. the code i sused id as under

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
        If Not IsPostBack Then
            Dim filePaths() As String = Directory.GetFiles(Server.MapPath("~/Result/comn/"))
            Dim files As List(Of ListItem) = New List(Of ListItem)
            For Each filePath As String In filePaths
                files.Add(New ListItem(Path.GetFileName(filePath), filePath))
            Next
            GridView1.DataSource = files
            GridView1.DataBind()
        End If
    End Sub

as of now all the files in that directory is displayed . i want to display only pdf files