In Twisted Wire Brushes, the filament material is twisted between two wires or four wire.
And there have below 3 constructions:
Single-Stem Single-Spiral – Filaments are twisted between two stem wires with a single layer of filament.
Double-Stem Single-Spiral – Filaments are twisted between four stem wires with two stem wires on each side. So this results in a brush with a much stronger base and potentially greater filament density.
Double-Stem Double-Spiral – Filaments are twisted between four stem wires with two layers of bristles. Each layer is perpendicular to the other with a single stem wire in each quadrant. So this results in a brush with the highest filament density and highest strength.