Kosher Tefillin Box Ultra Fine

What makes Tefillin Kosher?

1. Scroll must be written with ink.
2. The scrolls must be made of parchment.
3. The boxes and their stitches must be perfectly square.
4. On the right and left sides of the head-tefillin the letter shin must be embossed.
5. The scrolls must be wrapped in a strip of cloth.
6. The scrolls should be bound with kosher animal hair.
7. The stitching must be done with sinew of a kosher animal.
8. A ?passageway? must be made for the strap to pass through.
9. The straps must be black.
10. The straps should be knotted in the form of the letter dalet.

Tefillin Boxes are used for:
Tefilin is a daily mandatory mitzvah for men. While each morning (except Shabbat) a man should bless the tfilin while wearing it. Therefore the tefilin box is used to protect the actuall tefilin from wearing out by the daily use.

What is the tradition behind Tefillin Boxes?
The tefilin mitzvah was specificly directed from God to Moses : "And you shall bind them as a sign upon your arm, and they shall be as totafot between your eyes."