This is a Libman scrub brush, 2.5 inch, Rubber. Libman sets its fibres into the block under tension rather than gluing them to a backing pad, which is why the head keeps its shape instead of splaying after a few months of use.
Grout, tile and stubborn spots where a mop just glides over.
The Libman Company has made cleaning tools in Arcola, Illinois since 1896, and states that most of its products are made in the USA with US and globally sourced materials.









