Snap-on’s naming convention (Year.Quarter) means 21.4 = 2021, Quarter 4. However, support and feature backports for Solus Ultra continue through 2026. If you are looking for the very latest coverage (2025–2026), ensure your software is not older than 21.2 or 21.3.
The 21.4 update focused on improving technician workflow and expanding existing tool capabilities: Snap-on Cloud Integration snap-on solus ultra 21.4 update