Tefillin straps can become non-kosher with time. It is necessary to check and replace the when they are required to according to Torah law. Depending on their care, straps should last 10 years. Our sofer has a selection of straps to choose from. Straps are black on black, some are soft, some are firm, depending on your preference. Starting price $110. Sofer will replace the straps and custom-fit them to your head and arm size. It takes only a few minutes to change your non kosher straps to new kosher straps.