Prayer straps (Tefillin) are put on by Orthodox male Jews (and women, in more liberal congregations) during morning prayers. Tefillin consist of a pair of leather straps, which are put on following exact specifications – one around the arm, the other on the forehead. Attached to each strap is a box which contains four handwritten texts from the Five Books of Moses, from which the instruction to wear these prayer straps stems: Exodus 13:1-10 & 11-16, Deuteronomy 6:4-9 & 11:-13-21 as well as the Jewish creed “Shema Yisrael” (“Hear, O Israel”). They all contain the express commandment to “tie them [these words] for a sign upon your arm, and they shall be as tofalot between your eyes”. The wearing of Tefillin was already observed in antiquity.

Many discarded Tefillin are found in the Genizah, with some of them being very well preserved – including the small parchment scrolls found within the leather boxes. Even if the scrolls are still legible, the Tefillin most likely were discarded when the straps tore or were worn out.

Further Reading:
Rabinowitz, Louis Isaac: “Tefillin“ Encyclopedia Judaica, 2^nded., vol. 19, Detroit/New York, 2007.
Cowan, Alexander: Tefillin. A brief treatise. New York, 2005.