✔ 304 high quality stainless steel. Stainless steel is a common material with a density of 7.93 g / cm3, also known as 18/8. It exhibits good workability and high toughness up to a temperature of about 800 degrees. ✔ Various sizes of Plates Washer: M3 30PCS, M4 30PCS, M5 40PCS, M6 35PCS M8 40PCS, M10 40PCS, M12 10PCS, to meet different needs.It is a very essential manual tool for the family. ✔ With Flat Washers, the spring washer device is used under the nut to prevent the nut from loosening. Grower washers are used for loosening, flat washers do not have a loosening function, and flat washers only increase the contact area. ✔ The Plates Washers are arranged in a storage box, so you can easily find your way around the sets and avoid loss when needed. ✔ Application: Perfect for electrical connections on household and commercial appliances, automotive and marine uses where the power source has a threaded / bolt-type connection.