2826.19.10) Free No change No change On or before 12/31/2020 . 43. Sodium fluoride Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.42 Sodium Fluoride (CAS No. 7681–49–4) (provided for in subheading 2826.19.20) Free No change No change On or before 12/31/2020 . 44. Stannous fluoride Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.43 Tin fluoride (CAS No. 7783–47–3) (provided for in subheading 2826.19.90) Free No change No change On or before 12/31/2020 . 45. Sodium hydrogen difluoride Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.44 Sodium hydrogen difluoride (CAS No. 1333–83–1) (provided for in subheading 2826.19.90) Free No change No change On or before 12/31/2020 . 46. Chromium fluoride Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.45 Chromium(3+) trifluoride (CAS No. 7788–97–8) (provided for in subheading 2826.19.90) Free No change No change On or before 12/31/2020 . 47. Potassium bifluoride Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.46 Potassium fluoride hydrofluoride (CAS No. 7789–29–9) (provided for in subheading 2826.19.90) Free No change No change On or before 12/31/2020 . 48. Potassium fluoroborate Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.47 Potassium fluoroborate (CAS No. 14075–53–7) (provided for in subheading 2826.90.90) Free No change No change On or before 12/31/2020 . 49. Potassium fluotitanate Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.01.48 Potassium fluotitanate (Dipotassium hexafluorotitanate(2-)) (CAS No. 16919–27–0) (provided for in subheading 2826.90.90) Free No change No change On or before 12/31/2020 . 50. Potassium zirconate Subchapter II of chapter