Mezuzah, mezuzot, small encasements for parchment scrolls

Deuteronomy 6:4-9 NKJV  "Hear, O Israel: The Lord our God, the Lord is one! You shall love the Lord your God with all your heart, with all your soul, and with all your strength. And these words which I command you today shall be in your heart. You shall teach them diligently to your children, and shall talk of them when you sit in your house, when you walk by the way, when you lie down, and when you rise up. You shall bind them as a sign on your hand, and they shall be as frontlets between your eyes. You shall write them on the doorposts of your house and on your gates."

The mezuzah has always been both a device for remembrance by the Jewish people and a means of identifying the Jewish dwelling as a place where God is honored and revered. The mezuzah is affixed on the doorpost on the right side of the door at about eye-level (about one third of the way down from the top of the door). It is always inclined slightly inwardly (because even Gods Word bows before the Creator). In order to increase the mnemonic value of the mezuzah, one is placed on the entrance of every door in a house (except those for closets and bathrooms. [This information was obtained from the Holy Land Gifts website,  http://shofartallit.com/5163-5-pack-of-car-mezuzah-shaddai, 6-18-10.]

It is customary to write two inscriptions on the back of the parchment:

§                     the Hebrew word שדי (Shaddai)

§                     the phrase "כוזו במוכסז כוזו"

Shaddai, one of the biblical names of God, meaning Almighty God, also serves here as an acronym for Shomer Daltot Yisrael, "Guardian of Israel's doors". Many mezuzah cases are also marked with the Hebrew letter ש (Shin), for Shaddai.

"כוזו במוכסז כוזו" is a Caesar cipher — a one letter shift — of the third, fourth, and fifth words of the Shema, "Adonai, Eloheinu, Adonai", "The Lord, our God, the Lord"; it is written on the back of the mezuzah, opposite the corresponding words on the front.[6] This inscription, dates from the 11th century and is found amongst the Sages of Germany. [From wikipedia, http://en.wikipedia.org/wiki/Mezuzah, 06-18-10.]