Steel bolts, Dnepropetrovsk region.

"
Bolts are one of the most used types of fasteners. They make it possible to create a strong connection by screwing the rod into the hole using a nut or internal thread.(//tractor-service.com)
Classifying bolts into groups, they are divided by parameters: by material; by the shape of the head; by appointment; by coating and strength class.
Bolts also belong to different groups according to their purpose, which unite them according to their scope of application. Thus, it is possible to distinguish plow bolts, machine-building bolts, furniture bolts, and others. They can also be divided according to the shape of the product itself: bolts with a hexagonal head, with a semicircular head, eyebolts, hinge bolts, anchor bolts, bolts with a countersunk head and others. The main characteristics and requirements of these fasteners can be found in the documents of the corresponding GOST, DIN standards.
"