Menahot 35: What If Tefillin Were Blue?

More on tefillin, of course. The base of the box of the tefillin, the letter Shin on the tefillin, the black straps, among other details - are all "halakhah le-Moshe mi-Sinai" (not subject to dispute). Plus, a story about a few people who wore tefillin that did not follow the basic rules (blue wool instead of black leather, for example), and they were somehow not rebuked accepted. Also, the case of tefillin that tore. And the fact that their sanctity protects them from being used for anything else. Plus, measurements for the straps of tefillin. Also, what about God's tefillin? And the knot thereof? And what they contain?