In which situations does one fast if his tefillin fell to the floor? May one eat, drink, or nap while wearing tefillin? How often should one have his tefillin checked to ascertain their kosher status? What constitutes a left-handed person regarding wearing the shel yad on one’s right hand? The laws and customs surrounding the mitzvah of tefillin are numerous as they are intricate-yet they are crucial for every Jewish man to master. In The Tefillin Companion, Rabbi Yaakov Shmuel Marcus offers a clear summary of all pertinent laws and information, following the order of theShulchan Aruch. This sefer is an invaluable guide for both Ashkenazi and Sephardi tefillin- wearers, as it includes the laws pertaining to both sects. Written in an easy-to-read format, The Tefillin Companion is sure to become your go-to sefer regarding any and all tefillin questions that may arise.