Adjustable work stand

Hi
I recently came across a useful adjustable work stand during a talk
Unfortunately he refused to tell us where he got it from so here is a description in case anyone else is willing to share the big secret
It consists of 2 square aluminium platforms about 10" square connected by a concertina arrangement through the centre of which is a screw thread and a knob that when turned raises or lowers the upper platform

Thanks
Mark