The mark consists of the three dimensional, visible configuration of a stepped-recess housing and of a pivotal d-shaped handle that is nestable within a generally circular recess portion of the housing; with a generally flat mounting flange defining a front wall of the housing that is substantially flat so as to define a front wall plane of the housing, with mounting flange portions extending circumferentially about the circular recess; with the circular recess being defined by a generally cylindrical side wall that forms a rounded, smooth and uninterrupted juncture with such mounting flange portions as extend circumferentially about the circular recess, and with the side wall extending rearwardly from the front wall to form a smooth, uninterrupted, circular juncture with a generally round back wall that is substantially flat and forms a back wall of the housing; with a generally c-shaped trough being defined by the back wall and opening forwardly into the recess; with the c-shaped trough having a flat bottom portion when viewed in cross section, and with opposed ends of the trough being substantially trapezoidal shape and being spaced by a segment of the back wall; with the generally flat mounting flange having portions that extend continuously and contiguously in said front wall plane in directions extending radially outwardly from the circular recess so as to define substantially flat mounting flange having first and second opposed pairs of edge portions that give the mounting flange a generally square shape, but with the four edge portions that define the generally square shape each being curved convexly outwardly as they extend successively among and connect four corner regions of the mounting flange; with the corner region junctures of the edge portions being rounded to smoothly join end segments of the edge portions; with the circular recess being located substantially equally spaced between the opposed edge portions of the first pair, and with the circular recess being located substantially equally spaced between the opposed edge portions of the second pair so as to be located substantially centrally with respect to the generally square shape of the mounting flange; with the d-shaped handle including a bar member of generally rectangular cross section that extends substantially diametrically across the recess, but with the bar member being shorter in length than is the diameter of the recess so as to permit end regions of the bar member to be spaced inwardly from the circular side wall of the recess; with end regions of the bar member being pivotally joined to opposed end regions of a c-shaped handle grip; with the bar member having a substantially flat, forwardly-facing front surface that extends in a plane that substantially parallels the front wall plane; and, with the handle grip being substantially semi-circularly curved about an imaginary circle that is smaller in diameter than is the diameter of the circular recess, whereby the c-shaped grip can be nested within the recess or can be pivoted to project outwardly from the recess so as to extend forwardly from its junctures with opposed ends of the bar member.