Abstract: A paint brush kit and a bristle head cassette (1) for a paint brush, comprising a cassette collar (20) and a bundle of bristles (10) comprising a plurality of bristles (14), wherein the bundle of bristles (10) have a first bundle end (11) and a second bundle end (13), the bristles (14) of the bundle of bristles (10) being arranged aligned at the first bundle end (11) obtaining a substantial flush bundle end surface (12) at the first bundle end (11) of the bundle of bristles (10), the cassette collar (20) comprise; a recess (24) having a shape that substantially corresponds to a cross sectional shape of the first bundle end (11) of the bundle of bristles (10) and the recess (24) extend from a first collar end (21) having a first collar end surface (22) to a second collar end (23) opposite the first collar end (21), the bundle of bristles (10) is connected to the cassette collar (20) and arranged in said recess (24) such that the substantial flush bundle end surface (12) of the bundle of bristles (10) is substa