The housings are 4.4 cm x 4.4 cm and are painted with a hard shinny lacquer finish similar to those used in old pill-sized tefillin from the period. Besides encasing the entire batim, the paint also extends to the underside of the base creating a case of Hatzitzah for the wearer.
Their construction is very different than our modern tefillin. These would roughly fall into our category of Peshutim, but certainly not perudot. The divisions for the four interior housings of the Shel Rosh are created by gluing three separate pieces of leather to the interior of the head compartment, while the division lines from the outside remain purely cosmetic.
Upon checking the parashiot, the writing is within the"Alter Rebbe" family. The parchments had been checked by a different sofer in the past, and the last parasha of the shel yad -(Vehaya i'm Shamo'a) - replaced with a smaller modern Arizal. Unfortunately, upon my checking, the shel yad did not check-out properly. Some of the letters, although correctable, were not "makaf gevil." The landmine, however, in this type of writ; many times involves the writing of the letter BET. Five generations went by using a passul shel yad because a BET in the tefillin has the DIN of KHAF!
I have large older Russian parashiot that are still kasher and could technically replace the entire Shel Yad. However, if refurbished, the housings would still be Bedieved. What would you do? Refurbish or buy new?