# DIN 7989-1 — DIN / ISO / BS fastener equivalents and the sizes where they are not interchangeable For DIN 7989-1, part is Washers for steel structures - product grade C, verified against its source on 2026-08-05. - **DIN standard:** DIN 7989-1 _(verified: appears in the quote below)_ - **Part:** Washers for steel structures - product grade C _(verified: appears in the quote below)_ ## What the source says > DIN 7989-1 | | | Washers for steel structures - product grade C | ## Source - https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards Last verified: 2026-08-05. Review by: 2029-08-04. Part of [DIN / ISO / BS fastener equivalents and the sizes where they are not interchangeable](https://referencesource.org/fastener-standard-interchangeability-exceptions/).