a clamp assembly for installation at any position along the length of a slot defined by surfaces of a host structure or other structure . the clamp assembly either can receive a mounting rod for supporting objects or can itself include a mounting rod for supporting objects . in one embodiment the clamp assembly includes a two - piece clamp body composed of a pair of opposing substantially mirror - image jaws each having an inner surface with an arcuate channel and a tooth juxtaposing the arcuate channel . the arcuate channels cooperate to accept and frictionally engage a mounting rod to be affixed to the host structure , and the teeth are for entering into a slot defined by surfaces of the host structure . a tightening member is provided for forcing the jaws together . in an alternate embodiment the clamp assembly includes a one - piece clamp body and a mounting rod . the one - piece clamp body includes engagement tabs for entering into a slot defined by surfaces of the host structure and a threaded hole for receiving a threaded end of the mounting rod , which serves as a tightening member .