Factory engineered, self-contained, capillary tube system using environmentally friendly R290 hydro carbon refrigerant that has zero (0) ozone depletion potential (ODP), & three (3) global warming potential (GWP). Patented forced-air design holds 33°F to 41°F (0.5°C to 5°C) product temperature in food pans and cabinet interior. Please Note: No commercial warranty exists for domestic premises.