9902.11.89 - Expanded poly(tetrafluoroethylene) (PTFE) nonadhesive cellular sheets, of a thickness greater than 3.0 mm but not more than 6.0 mm, certified by the importer as having a tensile strength of at least 48.3 MPa (7,000 psi) per ASTM F-152 (CAS No. 9002-84-0) (provided for in subheading 3921.19.00)

This HTS category, 9902.11.89, specifically addresses expanded poly(tetrafluoroethylene) (PTFE) cellular sheets that are nonadhesive and have a defined thickness range of greater than 3.0 mm but not more than 6.0 mm. Crucially, for classification under this provision, the importer must certify that these sheets meet a minimum tensile strength of 48.3 MPa (7,000 psi) as determined by ASTM F-152, with the material identified by CAS No. 9002-84-0. This specialized classification falls under Section XXII, relating to temporary legislation and modifications, and indicates a particular set of conditions or restrictions apply to these specific PTFE sheets.

Given that this is a leaf node within the HTS database, it does not have further subdivisions. Its distinction from other potential categories within Chapter 99 lies in its highly specific product definition, encompassing not just the material (expanded PTFE) and its form (cellular sheets), but also precise physical parameters such as thickness and certified tensile strength. While other HTS codes might cover PTFE in general or sheets of different dimensions or properties, this subheading targets a very particular type of product that meets stringent technical specifications. The "provided for in subheading 3921.19.00" note indicates that the underlying commodity classification is elsewhere, but this Chapter 99 provision imposes a special or temporary rule.