ISO 5295, the international standard for synchronous (timing) belts, was revised in 2024. The changes mostly tighten measurement methods and bring marking requirements in line with newer metric-pitch profiles.
Key changes: a single reference temperature for length measurement (now 25 °C, was ambient), explicit marking rules for AT / HTD / RPP profiles, and a revised quality grading table that aligns ISO 5295 with ISO 13050 (automotive belts).
For most users, the practical impact is small — the belts you already use still pass — but you may see new markings on packaging and on the belt backs themselves as manufacturers roll out compliant production.