Rugged stackable merchandise tray containers are provided with right-angled mounting tabs at the inner corners of the top panel of two load supporting casing formed at the two ends of the tray container. The right-angled mounting tabs are engageable with rectangular mounting openings formed at the bottom of the bottom panel when two tray containers are stacked one on top of another. The mounting provide resistance to accidental external impact exerted to the stack. At least one trapezoidal shape pull-out tabs are also provided at the edge portion of the bottom panel, which are engageable with aligned mounting slots formed at the top panel of the load supporting casings to provide further securement of the stacked tray containers as well as enhanced resistance to external impact to the stack.