Patent ID: 8505145

Claim:
A substantially cylindrical central core for a cleaning sponge roller, comprising: a bore extending in an axial direction; and a plurality of small holes communicating between the bore and a circumferential outer surface of the central core, wherein at least eight axially elongated projections are provided along a circumference on the outer surface of the central core, the projections are substantially board-shaped ribs rising from the outer surface of the central core, a transverse section of each of the projections viewed from a direction perpendicular to the axial direction has concave and convex portions, a height between the concave and convex portions is 0.3 to 5 min, at least four convex portions are provided on a virtual straight line parallel to the axial direction of the central core, a plurality of the concave portions and convex portions are each arranged in different alternating patterns on the circumferential surface of the central core, and the projections are integrally coupled to ribs extending in a circumferential direction.