These Tefillin Dakkot are made in Israel by "Pe'er HaSTaM," proofread by an expert as well by a computer, and Certified Kosher. The Certificate demonstrates the proofreading and Kashruth level of the Tefillin that comes with a ten year warranty.
They are made by stretching (a thin layer) of one piece of parchment, which is Halachially preferable, over a structural base. The 33mm boxes of Tefillin Dakkot are considered higher quality, durable and larger than those of Tefillin Peshutim Mehudarim.
The differences: Tefillin Dakkot Ohr-Echad are covered with an additional layer of parchment than Tefillin Dakkot. However, Tefillin Dakkot are finished in a slightly superior manner compared to Tefillin Dakkot Ohr-Echad which are Halachically superior.
The script is called ktav ari - ari being the Hebrew acronym for Rabbi Yitzchak Luria. Preparation time is approximately 3to 5 days.