The BigHead Female Hex Nuts F1/B19 are produced in the United Kingdom and comply with international regulations regarding industrial products. These bonding fasteners can be attached via adhesives or via molten or manufacturing methods and the flat perforated head means the product securing locks into position. The products are made using mild steel, available in quantities of 25 and available in M4 thread size. If your construction, marine or automobile needs match this product, then the F1/B19 is the fastener for you.