A heat shrink tunnel with width adjustment includes a pair of opposing side wall assemblies, each including an outer wall and an inner perforated wall defining a plenum therebetween. The opposing side walls define a product path with the side wall assemblies being movable toward and away from each other. A heater/blower assembly disposed in each of the opposing side walls and has an outlet directed into the product path. A shroud extends over the side wall assemblies and an open top space between the side all assemblies. The side wall assemblies extend upwardly toward an inside of the shroud so as to define a small gap between tops of the side wall assemblies and the inside of the shroud. The shroud has a bottom wall. A conveyor is configured to convey items through the heat shrink tunnel. A tunnel includes a side wall assembly width adjusting assembly to move the side walls toward and away from one another by actuation of a single actuator.