secured to the bottom of each lower leg 604 e g via welding the attachment plates 608 have a plurality of openings 610 four openings in the preferred exemplary embodiment which are sized for receiving screws bolts or the like for attaching the lower legs 604 to the top of a steel or wood beam floor joist floor or the like 612 in the present embodiment the lower legs 604 may have a plurality of openings 614 located at spaced apart intervals e g on two inch centers on the front and rear of the square tube and a second plurality of openings 640 are located in the preferred exemplary embodiment at spaced apart intervals e g on two inch centers on the left and right side of the square tube between the plurality of openings 614 the plurality of openings 614 and second plurality of openings 640 may be located at any desired interval based on the intended use of the support unit 600 the lower legs 604 telescope into the l bars 606 the l bars 606 are square tubes composed of metal or metal alloy with an inside dimension which makes a sliding fit with the outside dimension of the lower legs 604 the l bars 606 have clearance openings 620 for receiving fasteners 622 such as pins clevis pins thumb screws nuts and bolts or the like which align with the plurality of openings 614 and 640 in the lower legs 604 for attaching the l bars 606 to the lower legs 604 located at the top of each l bar 606 is a horizontally extending arm 616 which is attached to the upright portion to form the l bars 606 the l bars 606 may be.