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

For 555, fastener description is Hexagon nuts; Metric Thread, Type g; iso equivalent is 4034; interchangeability is Width across flats according to DIN ISO 272 included; nominal diameter reduced; modification notes is Width across flats according to DIN ISO 272 included; nominal diameter reduced, verified against its source on 2026-08-12.

- **DIN standard:** 555 _(verified: appears in the quote below)_
- **Fastener description:** Hexagon nuts; Metric Thread, Type g _(verified: appears in the quote below)_
- **ISO equivalent:** 4034 _(verified: appears in the quote below)_
- **Interchangeability:** Width across flats according to DIN ISO 272 included; nominal diameter reduced _(verified: appears in the quote below)_
- **Modification notes:** Width across flats according to DIN ISO 272 included; nominal diameter reduced _(verified: appears in the quote below)_

## What the source says

> Hexagon nuts; Metric Thread, Type g | 555 | 4034 | 24034 | 4034 | 4034 | 2001-03 | Hexagon nuts – Product grade C | Width across flats according to DIN ISO 272 included; nominal diameter reduced |

## 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 **Hexagon nuts; Metric Thread, Type g**, as of 2026-08-12.

> Hexagon nuts; Metric Thread, Type g | 555 | 4034 | 24034 | 4034 | 4034 | 2001-03 | Hexagon nuts – Product grade C | Width across flats according to DIN ISO 272 included; nominal diameter reduced |

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

trfastenings.com says fastener description is **M5 to M100x6 Hexagon Nuts - product grade C**, as of 2026-08-12.

> DIN 555 | ISO 4034 | | M5 to M100x6 Hexagon Nuts - product grade C |

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/).