An improved housing for a roll-on has an inward end, an outward end and a side-wall having an interior surface extending from the inward to the outward ends, the outward end defining an aperture sufficiently narrow to retain the roller and permit a segment of the roller to extend outside the housing, and a spider mounted laterally within the housing on the interior surface of the side-wall at or adjacent to the inward end which spider is resiliently biased towards the roller and has a means for providing localised contact with the roller and providing a parallel spacing between the spider and roller. Especially desirably, the roller is a spherical ball.