Material: Square nut are made of high quality 304 stainless steel. Stainless steel 304 is a material widely used in hardware, robust, durable, wear-resistant, rust resistance, reusable and long life. Package content: 185 pcs square nuts (5 sizes: M3 * 60, M4 * 50, M5 * 40, M6 * 20, M8 * 15), with plastic storage box. There are 6 different sizes of square nuts that you can select depending on the use. Easy to store: Our square nuts with robust plastic storage box for a storage and convenient transport, to meet your daily needs. High resistance: The square nuts have a larger surface that is in contact with the part to be fixed, and therefore offer greater resistance against loosening. Square nuts are used with flat washers to avoid damage caused by their sharp edges and help increase the resistance of the attachment. wide application: Strong and anti-rust, excellent for indoor and outdoor use, widely used in home, equipment, agriculture, army, other industrial machines. and