Cowhide (gassot)
“Gassot” are made from thick cowhide, tanned under great pressure, and form a perfect square. The entire Bayit from top to bottom, including the inner partitions of the Shel Rosh, is made from a single piece of leather. Good quality cowhide tefillin will retain their perfect square shape, and their original black color. This is in keeping with the preferred halachic standard.

Identifying Cowhide Batim
One way to identify cowhide Batim is through the distinctive sinew grooves. These can be seen when examining the underside of the Batim. They do not exist in Batim made of sheepskin.

How to Choose Cowhide Batim
It is important to examine the Batim before they are dyed to ascertain that there are no holes or depressions which would disqualify the tefillin. Likewise, there should be no holes filled in with glue. The tefillin should be perfectly square and the grooves of the Bayit Shel Rosh should reach the seam.

How Tefillin of Cowhide are made

Tefillin shel Yad as seen from above

Stage 1

Stage 2

Tefillin shel yad as seen from below

Stage 1

Stage 2

Tefillin shel rosh as seen from above

Stage 1

Stage 2

Tefillin shel rosh as seen from below

Stage 1

Stage 2

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