There are many names used for this type of refrigeration systems some refrigeration professionals call them Self Contained Refrigeration Systems, some others call them Drop-In Refrigeration Systems and others call them Penthouse Refrigeration Systems. Whatever the name they are all the same type systems, these systems are all inclusive in one main insulated metal box, they have the evaporator, the accessories and the condensing all included inside the insulated metal box, most of the systems bring their own plug cord and all you have to do is plug the cord in to an electrical outlet depending on the required voltage and amperage and set the temperature controls and go. The air inside the walk-in is drawn up through the evaporator coil located within the insulated metal box housing the condensing unit and the evaporator, the self contained refrigeration systems sits on top of the walk-in through a ceiling cutout. A licensed refrigeration technician will be needed to fine tune the refrigeration system. These systems will sometimes seem higher in upfront cost but when all things are considered your cost for installation of a split refrigeration system versus these self contained refrigeration systems will be much less because the self contained refrigeration system is factory assembled and does not take up space inside the walk-in and it is less expensive in the long run. See pictures in the description pages below or click the link to the video.