Extremely large Tefillin

I recently had what is believed to be a very old set of tefillin passed onto me (for my grandson when he comes of age). This set is believed to be around 100+ years old, likely from Poland/Lithuania, but not known for certain. Both the sel yad and sel rosh are really large--have never seen anything like it before. There’s a mystical shin and other shin on them. Might you know of a sect or following that might have followed such a tradition? I really don’t know more about it or how my family is linked to this set. It was simply passed onto us from a very distant relative in Ashdod, Israel. They didn’t even provide a name. Looking forward to more info, direction. Thank you.

There is no limit to how big the Tefillin can be as long as it has the right square shape. Today Chabbad are known to use them. The tradition probably came from the great "Ba'al Hatanya". There are also "Mekubalim" (Kabbalists) that use them. Rabbi Binyamin Bamberger.