A square head bolt has a four-sided head. Compared to standard hex bolts, square bolts have a greater surface in contact with the part being fastened, and therefore provide greater resistance to loosening (though also greater resistance to tightening). Square bolts are typically mated with square-headed nuts.
| System of Measurement | Inch |
|---|---|
| Thread Size | 5/16"-18 |
| Fastener Length | 1-3/4 in |
| Material Grade/Class | Grade 2 |
| Material | Steel |
| Finish | Zinc Plated |
| Thread Type | Coarse |
| Item | Square Head Bolt |
| Head Type | External Square |
| Diameter | 5/16 in |
| Head Style | Square |
| Country of Origin (subject to change) | China |
| Package Quantity | 10 |