Abstract: A brush for cleaning corrugated surfaces has a multiplicity of bristles extending across the width of an elongated body. The bottom ends of the bristles form a virtual surface complementary to the corrugated surface. The bristles include a first set of bristles positioned to engage the ridges of the corrugated surface and a second set of bristles positioned to extend into the grooves of the corrugated surface. The first set of bristles have a first hardness, and the second set of bristles have a second hardness harder than the first hardness. This provides greater cleaning action in the hard to clean bottom surface portions of the grooves.

Abstract: A brush for cleaning corrugated surfaces has a multiplicity of bristles extending across the width of an elongated body. The bottom ends of the bristles form a virtual surface complementary to the corrugated surface. The bristles include a first set of bristles positioned to engage the ridges of the corrugated surface and a second set of bristles positioned to extend into the grooves of the corrugated surface. The first set of bristles have a first hardness, and the second set of bristles have a second hardness harder than the first hardness. This provides greater cleaning action in the hard to clean bottom surface portions of the grooves.

Abstract: An externally threaded nipple (24) fits through a circular opening (38) in a flexible wall (14). The nipple (24) is carried by a first ring member (18). An internally threaded second ring member (20) is screwed onto the nipple (24). The first and second ring member (18, 20) become connected together and the portion of the flexible wall (14) that immediately surrounds the opening (38) is trapped by and between two inner side surfaces (30, 36) of the two ring members (18, 20). Projecting portions (50) on one of the inner side surfaces are urged against the wall (14) to inhibit rotation of the attachment (16). One of the ring members (18, 20) has louvered fins (42) interconnected by strengthening ribs (44).