and an upper end of the cylindrical body of the movable grip 45 is substantially flush with the upper end of the sleeve 46 the movable grip 45 is secured to the sleeve 46 by means of for example a rivet 450 the fixed grip 44 comprises a cylindrical body with a palm holding extension 441 extending therefrom preferably in a direction substantially transverse to the finger holding extensions 451 of the movable grip 45 the cylindrical body of the fixed grip 44 has a central bore 442 with a reduced inner threaded section to threadingly engage and is thus secured to the upper threading 410 of the shaft 41 the shank 42 that is movably received within the shaft 41 has an upper end extending out of the upper end of the shaft 41 for securing and supporting thereon a manual button 424 which is movably received within the central bore 442 of the fixed grip 44 with a compression spring 43 located therebetween the compression spring 43 forces the button 424 and the shank 42 secured thereto to move upwards in a regular upright operation status relative to and away from the hollow shaft 41 and the fixed grip 44 secured to the shaft 41 the outer tube 1 the intermediate tube 2 and.