New Holycow bag. Leave a comment Blog: Diary of a sofer: See the issues that Rabbi Michaels deals with on a daily basis. February 4, 2013 Holycow tefillin bag made from cowhide. If you like this bag I will put you in touch with Rivky Kaufman who makes these bags. The one shown here is winter coat calf hide. It is very soft and is of interest to all who see it.