How can I display only specified database results based on TListbox items?

I have two forms: frmMakeQuote and frmQuoteTemp

In the frmMakeQuote there are two TListboxes: lboMtrlList and lboSelectedMtrl

lboMtrlList displays the Product Description column from the database.

procedure TfrmMakeQuote.FormCreate(Sender: TObject);
begin
  con := TFDConnection.Create(nil);
  query := TFDQuery.Create(con);
  con.LoginPrompt := false;
  con.Open('DriverID=SQLite;Database=C:\Users\kasio\Documents\Embarcadero\' +
    'Studio\Projects\ProgramDatabase;');
  query.Connection := con;

  query.SQL.Text :=
    'SELECT [Material Description] FROM MtrlDatabase ORDER BY MtrlID';
  try
    query.Open;
    lboMtrlList.Items.Clear;
    while not query.EOF do
    begin
      lboMtrlList.Items.Add(query.Fields[0].AsString);
      query.Next;
    end;
  finally
    query.Close;
  end;
end;

When the person double clicks on any 'product' in the lboMtrlList, it's moved to the lboSelectedMtrl. (Basically, it shows the selected 'products'.)

procedure TfrmMakeQuote.lboMtrlListDblClick(Sender: TObject);
begin
  lboSelectedMtrl.Items.Add(lboMtrlList.Items.Strings[lboMtrlList.ItemIndex]);
end;

I want to be able to display the Product Description and Price columns from the database, of ONLY the selected 'products' from the lboSelectedMtrl. They should be displayed in the TStringGrid called sgdMaterials on the frmQuoteTemp.

I wrote something like this:

procedure TfrmMakeQuote.performMtrlQuery;
var
  i: integer;
begin
   for i := 1 to frmMakeQuote.lboSelectedMtrl.ItemIndex do
   begin
  query.SQL.Text := 'SELECT [Material Description], Price FROM MtrlDatabase ' +
   'WHERE [Material Description] = "'
   + frmMakeQuote.lboSelectedMtrl.Items.Strings[1]
   + '" ORDER BY MtrlID';
  query.Open;
  query.First;
   end;
end;

It doesn't show any error, but it doesn't work and displays nothing and I'm aware that it's probably completely wrong.