The class 8.8 steel hex bolt has a zinc blue-chromate plated finish and an external hex drive, and meets Deutsches Institut fr Normung DIN 931 and International Organization for Standardization ISO 898 specifications. Class 8.8 steel, composed of quenched and tempered medium carbon steel, is often used in applications where strength is the primary concern. The material is magnetic. The zinc blue-chromate plating resists corrosion and has a blue reflective appearance. The external hex drive has six flat sides that a wrench can grip to turn the screw from the side, enabling use when there is no space above the head for a driver.Cap screws and hex bolts are threaded fasteners with thick hex-shaped heads that can be used with threaded nuts or in areas with limited clearance above the tapped (threaded) hole. Cap screws have slightly different dimensions than hex bolts and have a washer face underneath their unflanged hex head to act as a large bearing surface against the mating material.