Flow blocking device for an open refridgerated display case

An open refrigerated display case 2 comprising a refrigerated display volume 15; an air outlet 20 configured to direct airflow out of the air outlet across the display volume toward an air inlet to thereby form an air curtain across the display volume; a flow stabilising device 128 and a duct 16 fluidically connecting the air outlet and air inlet; and a flow blocking device 400 arranged at the air inlet or within the air duct, the flow blocking device configured to block a portion of the flow area through the air inlet or the duct. The device may be affixed over the inlet using magnets, or fasteners inserted into a grille. The device may block between 40-80% of the area of the air inlet or duct. A blocking plate for blocking the air inlet of the open refrigerated display case is also provided.