A clamping device is provided to be secured to articles such as patio furniture to mount an umbrella or the like. Clamping jaws engage the article of furniture and there is a holder for mounting the umbrella to provide a first position permitting pivotal movement of the holder and a second position in which locking teeth inter-engage to prevent pivotal movement. There are means for normally securing the first section to the second section in a position where pivotal movement is prevented.
