A Kosher Mezuzah Scroll is a portion of Holy Torah that has been inscribed in the same manner and script as a Torah. It is an "original" sanctified document in accordance with laws and precepts that dare not be compromised.
On this sacred scroll of parchment are inscribed two passages from Torah, "Shema Yisroel" and "Vehaya" (Deuteronomy 6:4-9 and 11:13-21). Because it represents basic principles of our faith, the Mezuzah is our responsibility to visitors as well as to ourselves. When a Mezuzah is not valid, its blessings are nullified. Even if one letter or part of a letter is missing or imperfect, the Mezuzah may not be used.
Only a "Kosher" Mezuzah sanctifies and protects the home, as well as fulfills the saying of the Psalmist, "G-d will guard your going and coming from now and for all time." That is why when you purchase a Mezuzah for yourself or make it a gift to a relative or friend, you are obligated to assure its validity. Be certain that it is hand written and that you obtain it from a reliable source.
If it's written in Torah script by an ordained and dedicated scribe, then it identifies, sanctifies and protects your home with its blessing.
Just as a Torah is adorned with ornaments, the Mezuzah is encased in any variety of traditional or contemporary cases. The contents, however, may never be compromised.