outwardly over the ground plate 12 this retainer 31 is formed of a high density rubber or the like having a substantial thickness and limited flexibility the retainer 31 is mounted upon the ground plate by means of an upper rigid plate or rim 32 having a central aperture 33 that is slightly larger than the plate 27 affixed to the bottom of cylinder 14 to form the flange 27 thereabout this upper plate 32 is also formed as a rigid structural element from steel or the like and is attached to the ground plate by clamping means such as bolts 41 extending upwardly through the ground plate retainer 31 and the upper plate 32 with nuts and washers 42 and 43 provide atop the upper plate 32 in engagement with the bolts tightening the nuts 42 on the bolts 41 will clamp the retainer 31 between the ground plate 12 and upper plate 32 to force the retainer tightly against the cylinder flange 27 so as to lock the cylinder or post support means 14 onto the ground plate 12 the present systems as described above also includes mating apertures 46 through the bottom plate 28 of the cylinder 26 and the ground plate 12 so that water may drain from the post receiving member 14 to prevent rotting of the bottom of a.