3 when it is screwed into the collar 2 when the invention is fully assembled the top circumferential portion 12 a of the bracket 12 also lies directly on top of the top edge 2 a see fig2 of the collar 2 the collar 2 has an inner top threaded portion 2 b sec fig2 and an inner bottom non threaded portion 2 c see fig5 the bracket 12 further comprises two vertical extensions 12 b that extend downward from opposite sides of the top circumferential portion 12 a and that end in the two bottom protrusions 12 c that are secured to the circumferential flange 1 b of the post 1 by bolts 13 as noted above the bottom end 3 a see fig2 of the barrel 3 screws into the collar 2 and the top cap 6 screws onto the top end 3 b of the barrel 3 which is also threaded in a preferred embodiment the top cap 6 preferably comprises a dust seal 7 that is situated around the perimeter of the inside bore of the top cap 6 the barrel 3 preferably comprises two apertures 3 c see fig4 that are longitudinally offset from one another a plug 11 is shown as being inserted into the higher of the two apertures 3 c the purpose of the apertures 3 c is discussed more fully in connection with fig1 fig2 is an exploded view of the present invention in this figure the top cap 6 and dust seal 7 are referred to as the top cap assembly 18 the barrel 3 and top and bottom bushings only the top bushing 4 is visible in this figure comprise the barrel assembly 19 the collar 2 and.