Over 15 years in the making, NL-19 is Foreverbolt’s proprietary lab-tested treatment that modifies the surface of stainless steel products, producing a brighter finish, increased strength, and superior corrosion resistance all without affecting the fastener’s exterior dimensions. – See more at: http://www.fastener-world.com.tw/new/news_detail.php?id=4523#sthash.ZpePViXm.dpuf