Recuperar un dato desde una BD(SQL) a TEXTBOX

Estoy viendo la manera de mediante una consulta recuperar un dato desde SQL para que este me aparezca en un textbox.

Os dejo el codigo para que, si podeis me echeis una mano, GRACIAS.

Private Sub ComboBox4_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox4.SelectedIndexChanged

        Dim envasebebida As String
        envasebebida = ComboBox4.SelectedItem.ToString


        Dim sqlConnection1 As New SqlConnection("Data Source=FRANCISCOXPS27\FRANCISCO;Initial Catalog=RESTAURANTE;User ID=sa;Password=*****")
        Dim cmd As New SqlCommand
        Dim reader As SqlDataReader
        cmd.CommandText = "SELECT  volumen_bebida  FROM configuracion_envase_bebida  WHERE envase_bebida = @envasebebida "
        cmd = New SqlCommand(cmd.CommandText, sqlConnection1)
        'Variables
        cmd.Parameters.Add("@envasebebida", SqlDbType.NVarChar, 255).Value = envasebebida
        sqlConnection1.Open()
        reader = cmd.ExecuteReader()


        TextBox1.Text = reader.ToString
        sqlConnection1.Close()
        reader.Close()

    End Sub