This product is a large washer made of SUS304 stainless steel (special dimension flat washer). The washer has a larger outer diameter than the standard size flat washer, so you can expect to reduce the phenomenon of the nut or bolt head into the clamping material (seated recess) and stabilize the tightening surface. Besides metal, it is also suitable for fastening FRP and wood etc. (*The first image is a representative image)