; and (B) by striking 12/31/2020 and inserting 12/31/2024 . (223) Flame retardant rayon fibers, 4.7 decitex Heading 9902.13.29 is amended— (A) by amending the article description to read as follows: Artificial staple fibers of viscose rayon, not carded, combed or otherwise processed for spinning, each containing 28 percent or more but not over 33 percent by weight of silica, measuring 4.7 decitex and 60 mm in length (provided for in subheading 5504.10.00) ; and (B) by striking 12/31/2020 and inserting 12/31/2024 . (224) Acrylic staple fibers processed and with a decitex of 2.75 to 3.3 Heading 9902.13.36 is amended— (A) by amending the article description to read as follows: Acrylic staple fibers, carded, combed or otherwise processed for spinning, containing by weight 92 percent or more of polyacrylonitrile, not more than 0.01 percent of zinc and 2 percent or more but not over 8 percent of water, dyed or raw white (undyed), with an average decitex of 2.75 to 3.30 (plus or minus 10 percent) (provided for in subheading 5506.30.00) ; and (B) by striking 12/31/2020 and inserting 12/31/2024 . (225) Acrylic staple fibers processed and with a decitex of 5.0 to 5.6 Heading 9902.13.38 is amended— (A) by amending the article description to read as follows: Acrylic staple fibers, carded, combed or otherwise processed for spinning, containing by weight 92 percent or more of polyacrylonitrile, not more than 0.01 percent of zinc and 2 percent or more but not over 8 percent of water, dyed, with an average decitex of 5.0 to 5.6 (provided for in subheading 5506.30.00) ; and (B) by striking 12/31/2020 and inserting 12/31/2024 . (226) Neoprene wading socks Heading 9902.13.51 is amended— (A) by amending the article description to read as follows: Socks with uppers comprising neoprene measuring 2.5 mm in thickness and covered on both sides with jersey knitted fabric of nylon; such socks with underfoots of breathable neoprene measuring 2.5 to 3 mm in thickness and covered on both sides with a jersey knitted fabric of nylon