Maaseh Rav Siman 19
Can copy this into an AI, or connect the whole library to your assistant. For deeper learning, you can directly use the original seforim, sites, and apps.
התפילין של ראש הבתים צריכין להיות פתוחות ולא מדובקים בדבק:
Sefaria Community Translation
The compartments of the head tefillin need to be open and not glued.