This letter, dated December 18, 2015, clarifies that the concrete tie produced by ROCLA Concrete Tie, Inc., is a component of a concrete tie-based fastening system in which the tie-mounted shoulder works in conjunction with the loose clips, mounts, and insulating pads to secure the rails to the tie.  Because the shoulders have been permanently incorporated into the ties during the manufacturing process, they are not separate components; rather, they are subcomponents of the concrete ties and are not required to be sourced domestically.