Phillips CSK Screw

These screws are very resistant to sea water and chemicals. Under the head, screws are inclined to fit flush into countersunk holes. 

Mild corrosion resistance is provided by a zinc plating. Under the head, these screws are angled to fit flush into countersunk holes. 

In addition to being nonmagnetic and electrically conductive, brass screws also resist corrosion well. These are positioned flush with countersunk holes at an angle beneath the head. 

A third of the weight of steel screws is made of aluminum, which also resists corrosion well. They are positioned flush within countersunk holes at an angle beneath the head.