Wire these screws together through the hole in the head for better vibration resistance than any other rounded head screw. They have fillister head with a deep drive to maximize driving power and a narrow diameter to fit in tight spaces. Made from 18-8 stainless steel, they have good chemical resistance and may be mildly magnetic. All are passivated to Fed. Spec. QQ-P-35 for added protection against oxidation and corrosion. Length is measured from under the head.