Scroll Encased in a Glass Tube

Question:

When I was in Israel, I bought a mezuzah cover which was a clear glass tube that is mounted on a wooden base — sort of a “message in a bottle.” I only noticed later that this would mean that the scroll will be suspended away from the doorframe. Can I use it?

Answer:

Yes. Since the tube is firmly affixed within a handbreadth of the door, the air and the wooden base do not constitute an interruption between the scroll and the door.^[1]

[1] Agur B’ohalecha, citing Da’as Kedoshim Y.D. 289:4 and R. Shmuel Wosner in Kovetz Mi-Beit Levi 2:23. Cf. Minchas Yitzchak 10:95. The gap between the mezuzah and wall must be less than a tefach.