Avraham Halpern asks:
Why is a mezuzah written on duchsustus while Tefillin are written on klaf?
Avraham Halpern, Queens, NY
The Kollel replies:
Dear Avraham,
The Gemara (Shabbos 079b, Menachos 32a) says openly- Halacha l'Moshe MiSinai- no Drasha, no reasoning. (see Shulchan Aruch Yoreh Deah 271:3, 288:6 that now Klaf is used.
All the best,
Reuven Weiner