public ListBoxModel doFillSizeIdItems(@RelativePath("..") @QueryParameter String authToken)
        throws Exception {

      List<Size> availableSizes = DigitalOcean.getAvailableSizes(authToken);
      ListBoxModel model = new ListBoxModel();

      for (Size size : availableSizes) {
        model.add(DigitalOcean.buildSizeLabel(size), size.getSlug());
      }

      return model;
    }