The unit is in two parts. Firstly, the unit has an insulating bag which the fluids are placed into. Also in the pack, is a re-useable heat pack, which when activated will provide an hour of heat. The fluids are placed in the insulated bag and this has a clip on the top to hang the unit up. The bag zips shut and has a toggled draw string to secure the fluids and prevent heat loss. There is a clear panel to allow a visual check of the fluids. The fluid is warmed in the bag and an insulated line cover prevents heat loss from the fluid prior to delivery into the body. Finally there is a small warmer pack which can be placed around the access site to warm the fluid at the site. The heat pack is manufactured from a heavy duty supple plastic and sits in a pouch to one side of the fluids. The unit is activated by squeezing a metal disc that floats in the liquid. The fluid then heats up and you massage the pack to get maximum heat output. It remains at a working temperature for about one hour. After this, the pack should be microwaved as per the instructions for 1.5 minutes or immersed in boiling water and allowed to simmer for about 15 minutes. This re sets the pack and it can then be re-activated the next time the kit is used Tests have proved across a range of temperatures from -5 or 20*C that infupak can raise the temperature of a variety of fluids between 1*C and 8*C. It should be noted that previously warmed fluids will benefit the most from the use of infupak and that performance varies according to the ambient temperature. Pack Is Wrapped Around IV Fluid Bag Warms The Fluids In Bag Insulated Line Cover To Prevent Heat Loss Prior To Delivery Into Body