The Straps

The straps are made of leather painted black on one side. They are threaded through the lower part of the boxes and knotted.

The head tefillin has a large, fixed loop to fit the head. The hand tefillin has a smaller, adjustable loop to tie on the upper arm.

The head strap's knot is in the shape of the Hebrew letter daled; the hand tefillin is knotted in the shape of the Hebrew letter yud. (Together, shin, daled, yud spell Sha-da-i -- one of the names of G-d.)