GUNI washers for use to prevent surface damage to GUNI Wheel and reduce the chance of over tightening lug nuts/bolts. Washer Style: Flat Washer Shape: Centered round Washer Material: Stainless steel Washer Finish: Natural Washer Outside Diameter (in): 0.591″ (15mm) Quantity: Sold as a set of 6 Washer thickness may vary between 3mm and 5mm