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The exact order of the four biblical passages (parshiot) within the tefillin shel rosh is critical; if they are not arranged in their specific sequence, the tefillin are disqualified. Abaye and Rava debate the specifics of this requirement, questioning the validity of the tefillin if the two "outer" sections (the first and last) or the two "inner" sections are transposed.

Several physical elements of the tefillin are classified as halakha l'Moshe m'Sinai: the embossed letter Shin on the Shel Rosh, the requirement for the boxes to be perfectly square, the titura (the base), and the ma'abarta (the passageway for the straps).

Regarding the straps (retsuot), the outer side must be black. The underside may be other colors, though red is strictly prohibited. If a strap is partially torn, it is disqualified. The Gemara distinguishes this from tzitzit or a hyssop branch, where "remnants" may still be valid; this is because tefillin straps serve an object of inherent kedusha (sanctity), requiring a higher standard.

The knot of the shel rosh must be shaped like the letter dalet (halakha l'Moshe m'Sinai). Rav Nachman rules that the knot should be prominent and face outward, reflecting the idea that tefillin serve as a sign to the nations that "God's name is called upon you." This purpose also dictates the exact placement of the knot at the base of the skull and the box on the head. Finally, the blessing is recited after the tefillin are placed but before the final wrapping or tightening is completed.