18 in a stationary position relative to the adapter mount 16 if the fastener 38 is loosened the support arm 18 can move relative to the adapter mount 16 if the fastener 38 is tightened the first half 34 a and the second half 34 b of the adapter mount 16 tighten around the support arm 18 and the support arm 18 cannot move relative to the adapter mount 16 fig3 illustrates a perspective view of the sliding clamp 30 that attaches the series of ball jointed links 20 to the support arm 18 the sliding clamp 30 includes a substantially square opening 46 that matches the shape of the support arm 18 in this example the opening 46 includes rounded corners 47 and linear sides 49 the corresponding rectilinear shape of the opening 46 and the support arm 18 prevent the support arm 18 from rotating about its own longitudinal axis in this example the sliding clamp 30 includes a first half 40 a and a second half 40 b that each include an opening 42 a fastener 48 shown in fig1 is received in the openings 42 to secure the first half 40 a and the second half 40 b.