6X3/4 Five Sixteenths Round Spacer Nylon RPFB while the 4 1/2 refers

while the 4 1/2 refers to the length of the bolt

* Type F head style

It is made of hardened steel and coated with black phosphate for corrosion resistance

and a hi-low thread pattern

The screw is made of alloy steel and has a zinc yellow DFAR finish

6X3/4 Five Sixteenths Round Spacer Nylon RPFB while the 4 1/2 refers**6X3 4 Five Sixteenths Round Spacer Nylon** This cylindrical spacer is made of durable nylon, providing excellent insulation and resistance to chemicals and abrasion. It features a round shape with a diameter of 5 16 inches and a length of 3 4 inches. The spacer has a smooth surface and precisely drilled holes for easy mounting. It is designed to create space between components, isolate vibrations, and prevent electrical shorts. Its lightweight and