The Relief Pak Heating Unit 4-Pack Capacity effectively heats moist heat packs up to 170° in an insulated hot water bath. Insulated design keeps heat from dispersing out of the unit, allowing it to retain heat. It is made from durable stainless steel that's perfect for high traffic clinics and its compact stationary design allows it to easily sit on a countertop. This heating unit features adjustable temperature control and a glowing orange light illuminates when the unit has reached its desired temperature. It is best to use moist heat packs at 160° for best results. An on/off switch glows green when the unit is in use. This unit has a 4-pack capacity that can heat up to 4 standard moist heat packs. A removable plug set comes with this 110V unit. A set of 4 standard Relief Pak HotSpot Moist Heat Packs come with this unit. These heat packs are reusable and can maintain therapeutic heat for up to 30 minutes.