action on the nuts 42 and bolts 40 for tightening or releasing the anchoring member 24 of the holding device 20 to or from the support structure s respectively is easily done using a standard ratchet wrench and a drive socket the positioning of the securing member 26 in close proximity to the resilient link 36 allows for a second and simultaneous function of the nuts 42 and bolts 40 of the securing member 26 of displacing the two jaws 32 of the grasping member 22 towards each other to tighten post p therebetween this second simultaneous function is the simplicity and the heart of this invention and is produced by the particular design explained herein the tightening of the nuts 42 on the bolts 40 produces a force almost perpendicularly to the axis of the bolts 40 forcing and closing action onto the opening 34 due to the flexion of the resilient link 36 which in turn closes the circular opening 38 tightly confining the umbrella post p in the circular opening 38 between the distal ends 44 of the jaws 32 of the grasping member 22 this is shown by the arrows a 2 on fig1 fig3 shows that if the distance between the two generally vertical bars of the support structure s of the.