On the tefillin shel yad, there is an outer black box that covers the actual tefillin box. Is this required?

  • If the ketzitzah loses its squareness, it becomes passul. As such, while it isn't required me'ikar hadin, the cheap plastic cover will save hundreds of dollars of repairs or replacement down the road Nov 30, 2023 at 4:59

1 Answer 1


Virtually all descriptions of tefillin construction in the early Rishonim and Geonim include an extra leather strap covering the hand tefillin box, sewn on the two sides and covering the top like a bridge.

Some described it as a practical protective piece and others described it as the תיתורא--bridge which the Talmud (Menachot 35a) says is a traditional requirement.

The Rama (OC 32 at the end) notes the practice and says he has never seen tefillin without this strap.

In places where the former interpretation held sway and tefillin were constructed sturdily enough, some people stopped bothering. It had already fallen out of fashion in Rav Joseph Karo's Spain and later in Ashkenazi lands.

Even if we think this was just about protection and plastic is fine, we can still recognize a strong tradition of actively protecting our tefillin that is alive and well. But there's also seemingly nothing to lose by getting a black leather cover as all our ancestors did and many Rishonim and Geonim thought was an absolute requirement.

  • Now you understand the whole chumra of taking off the plastic cover for the blessing: Tosafot (in one answer) says this strap isn't a problem of covering the box since it only covers two sides. If the plastic covers four sides then maybe it's now a problem!
    – Double AA
    Nov 30, 2023 at 2:11
  • 2
    Do you have any pictures of the leather covering sewn on two sides?
    – magicker72
    Nov 30, 2023 at 2:43
  • So you're saying the plastic cover is definitely not required? Or are there opinions that it's necessary as protection?
    – shmosel
    Nov 30, 2023 at 8:48
  • @magicker72 I've looked at old depictions of tefillin and never seen it, but there are very very few of them of any significant age. Here's a modern one hebrewbooks.org/pdfpager.aspx?req=65822&st=&pgnum=143 but it's not hard to imagine this in your head: just take a strip of klaf, paint it black, and bend it over the top of the bayit (perpendicular to the length of the arm). It could even go underneath a modern plastic cover and no one would know.
    – Double AA
    Nov 30, 2023 at 17:05
  • @shmosel I'm saying it's an age old venerated Jewish practice to protect the tefillin (accd to the opinions that that strap was about protection) not some modern innovation for cost saving. (Most people see plastic boxes and assume it's a new thing.) I'm not aware of any opinion that says protection itself is מעכב, though it certainly is very consistent with ושמרת את החוקה הזאת. Would seem foolish to dispense with it lightly if Jews have done it for so long.
    – Double AA
    Nov 30, 2023 at 17:05

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