by extending through locking aperture 42a also provided on supporting area 51 are a plurality of rotation control ribs one set 53 and 53 39 disposed on one side of coupling bar 52 define an escape groove 53a therebetween as best seen in fig9 a and 9b when the stand assembly is assembled first guide rib 43 of upper stand portion 41 is received in escape groove 53a diametrically across from ribs 53 and 53 39 is a resilient tab 54 which is downwardly movable and is formed by a separating slit 54a resilient tab 54 includes an upwardly protrudent rib 55 and an l shaped downward knob 56 protrudent rib 55 has a vertical side wall portion and a sloped portion adjacent to rib 55 is another rotation control rib 57 so that second guide rib 44 of upper stand portion 41 is received therebetween referring now to fig8 a and 9b the preferred embodiment of the present invention will be explained in detail in conjunction with the assembly and operation thereof the monitor stand assembly comprises upper stand portion 41 and stand base portion 50 coupled together and adjusted to a suitable viewing position the preferred assembly is best seen in fig9 a and 9b to assemble the invention upper stand portion 41 and stand base portion 50 are first aligned with each other so that coupler bar 52 extends through locking aperture 42a thus the.