Cleaning Accessories
HEPA Filter Sponge Filters Side Brush, for Eufy for RoboVac 11 11c Robotic Vacuum Cleaner Filter Parts Accessories (Color : Filter and brush)
The measurement allowed error is +/- 1-3cm.
https://www.bizrate.co.uk/cleaning_accessories/hepa-filter-sponge-filters-side-oid31107023468.html