This Grip-Rite box nail set includes 16d 3-1/4" sinkers made of smooth steel material. The 5 lbs box contains 16ctdskr5 nails with a flat head style, perfect for home improvement projects and building needs. These nails are measured in inches and manufactured in China. Ideal for use in the construction industry or for DIY projects, this box nail set is a reliable and durable choice for any project.