A family of Microsoft word processing software products for creating web, email, and print documents.
It is a simple matter to make your own with the dimensions of the case that you want to use.
If you want sides, use a three column table with the row height and column widths set to the required dimensions and use the Rotate Text facility for the text in the first and third columns (the sides)
If you do not want the sides, just use a one row, one column table with the cell dimensions set the the required values.
Alternatively, use one of the Avery US Letter templates - 8691, 8692, 8693 or 8699 available via the Labels facility on the Mailings tab of the ribbon.
If the dimensions are not exactly what you want, click on the Details button on the Label Options dialog and make the necessary modifications