A bolt is a form of threaded fastener with an external male thread. Bolts are very closely related to screws. The distinction between a bolt and a screw is commonly misunderstood. The defining distinction (Machinery's Handbook) is in their intended purpose: Bolts are for the assembly of two unthreaded components, with the aid of a nut. Screws in contrast are used in components which contain their own thread, and the screw may even cut its own internal thread into them. Many threaded fasteners can be described as either screws or bolts, depending on how they are used.
Technical Parameters:
| Diameter | M20 mm | Material | Zink plated steel | |
| Head size | 30 mm | Thread type | ISO metric coarse | |
| Strength Class | 8.8 | Weight (100pcs) | 17.6 ÷ 38.1 kg |
