# 603 — Fastener standard equivalences: DIN to ISO / EN crossover

For 603, fastener description is Mushroom head square neck bolts; iso equivalent is 8677, verified against its source on 2026-08-12.

- **DIN standard:** 603 _(verified: appears in the quote below)_
- **Fastener description:** Mushroom head square neck bolts _(verified: appears in the quote below)_
- **ISO equivalent:** 8677 _(verified: appears in the quote below)_

## What the source says

> Mushroom head square neck bolts | 603 | | | | 8677 |

## Sources disagree

More than one authority states this, and they do not state the same
thing. Both are reproduced with the source each came from.

### Fastener description

fullerfasteners.com says fastener description is **Mushroom head square neck bolts**, as of 2026-08-12.

> Mushroom head square neck bolts | 603 | | | | 8677 |

Source: https://fullerfasteners.com/tech/din-iso-en-crossover-chart/

trfastenings.com says fastener description is **Mushroom Head Square Neck Bolts**, as of 2026-08-12.

> DIN 603 | | | Mushroom Head Square Neck Bolts |

Source: https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards


## Source

- https://fullerfasteners.com/tech/din-iso-en-crossover-chart/
- https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards

Last verified: 2026-08-12. Review by: 2028-08-11.
Part of [Fastener standard equivalences: DIN to ISO / EN crossover](https://referencesource.org/fastener-thread-standard-equivalence/).