This action finalizes certain amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP): Clay Ceramics Manufacturing source category. The final amendments are being issued in response to a petition for reconsideration filed by an affected industry (Kohler Company) on the final rule promulgated on October 26, 2015, as well as our review of the 2015 rule with respect to certain other issues raised by Kohler. This action revises the temperature monitoring methodology used to demonstrate continuous compliance with the dioxin/furan (D/F) emissions limit of the final rule. In addition, we are addressing concerns raised by Kohler regarding visible emissions (VE) monitoring of tunnel kiln stacks for continuous compliance with particulate matter (PM) and mercury (Hg) emission limitations. This action also amends the requirements for weekly visual inspections of system ductwork and control device equipment for water curtain spray booths. Lastly, this action amends the NESHAP to include provisions for emissions averaging, makes technical corrections, and adds certain definitions.