At the t’filin workshop, we had the opportunity to have our t’filin checked to make sure they were still kosher and in good shape. Rabbi Kreiser, of Keshirat Tefillin, came and showed us the correct way to wear our t’filin, and he carefully inspected the boxes to see that they were in good condition and that the paint on them was still kosher. It was interesting to watch the sofer examine every small detail: the boxes, the straps, and even the way they sit on our arm and head.