Traditional woven haircloth made from horsehair or coarse animal hair and used as tailoring interfacing falls here. However, nonwoven interlinings or those made from fine animal hair or synthetic fibers would be classified elsewhere. The fiber type and woven construction are both required for classification under 5113.

Classification turns on the fiber diameter thresholds set out in the chapter notes to Section XI of the HTS. Laboratory fiber analysis is the standard method when the origin species or fiber grade is not clearly documented. Suppliers should provide fiber specification sheets or test reports to support the declared classification.