The Pro-Bolt Drilled Alloy Washer is even more lightweight than flat washers and can be used with Allen Head Bolts to spread the load or prevent bolts 'pulling through'.This 100 piece workshop tub contains various sizes of drilled washer from M5 to M12.Material specification: 7075T73Anodising: Chemically brightened and colour anodised to between 8 and 12 microns thickWeight: 60% lighter than stainless steel - 40% lighter than titanium.Corrosion: Resistant to saltwater, road film and mild acids.Application: Aluminium is suitable for use in all non-safety critical areas. Aluminium is not suitable for any stress area applications.Sizes are thread diameter by outer diameter.