Hi, Judy.
Yep, them's tefillin.
They are considered EXTREMELY holy... on par with a Torah scroll.
The outer covers are probably plastic or cardboard. however the inner box and the straps are all leather from a kosher animal (usually a cow or bull). Inside the leather boxes are scrolls written on parchement with the verses of the "Shema" on them. Traditionally, they are used during morning prayer services on weekdays (not Saturdays or Jewish Holidays). They are worn by males age 13 and up.
I would be interested in knowing if the knot on the loop of the "head" tefillin is a box knot or an L-shaped knot. It would tell me whether the Teffilin in question are Ashkenazic or Sephardic. Just a matter of curiosity, not something that changes anything. The "head" tefillin is the one that does NOT have a slipknot. The "arm" tefillin has the slip knot.
Are you going to be keeping them? If not, there are a number of good charities that accept old teffilin and give them to young boys just becoming bar-mitzvah who cannot afford a pair for themselves. (A pair can run as high as $5K. The lowest I've seen in recent years is $2K.) If you'd like, I can put you in contact with such charities.
If you plan on keeping them, I suggest keeping them in a dry place without too much moisture in the air. The leather and the parchment of the scrolls is very sensitive to air moisture. We generally have our teffillin checked by an expert every 3 years or so for degredations of the leather and problems with the scroll because they are so sensitive. DEFINITELY keep the teffillin inside the pouch when they are not being used or shown in order to protect them from too much exposure.
Let me know what you want to do, and I'll be happy to assist you.
Elliot