This quality 1" square steel table leg is 30.5" tall and can be cut to length (the black end plug is removable). 

The leg locks down into position when in use, and it folds up when not in use. You will need to secure it in the up position with a latch as it does not lock in the folded up position. When you want to unlock it from the down position, simply press in the spring-loaded button on the side of the hinge.  

The sturdy steel mounting plate is attached under the table top.It is 2.625" x 1.75" and has holes sized for #10 screws.

The leg comes painted a glossy medium gray color, but you can paint it to match your interior.