Metric DIN 478 square head bolts with collar are externally threaded fasteners with a square shaped head with a washer face.
The head configuration of the DIN 478 square head bolts provides a significantly larger surface area and these bolts are used where larger bearing surfaces are required.
DIN 478 square head bolts are partially threaded with thread length dependent on the diameter and length of the bolt.
DIN 478 Square Bolts are previously used instead in place of hex bolts. Square bolts are easier to tighten using a wrench with a nut with a square shaped head.