a wide open rear post 28 being of tubular stock has an upper end cap 28b and carries sign 30 spaced downwardly therefrom a sufficient distance for slide guard 32 to provide the intended protection sign 30 having lettering 30a providing an appropriate warning message on the front facing surface thereof is suitably attached to post 28 as by bolt and nut fasteners 31 the orientation of the front facing surface of sign 30 likewise determining the front side of post 28 and dictates the alignment thereof with base 21 and vertical housing 25 post 28 has the lower end thereof coaxially mounted on helical tension spring 26 which is connected to vertically upstand from the center of base plate 22 concentrically surrounded on the front side thereof by curved front wall 25b of vertical housing 25 whereas the parts may be connected by welding however to facilitate shipping in a knockdown condition and for ease of assembly post 28 and spring 26 are sized for the latter to telescope into the lower end of post 28 and be secured therein by clamping collar 29 having radially extending end flanges 29b formed with aligned openings for adjustable clamping therethrough by nut and bolt 29c a short longitudinal slot 28a at the telescoped end portion of post 28 permits tightening of the.