The thermoguard jumpsuit was an expensive form of bodysuit that was developed to allow the wearer to become invisible to infrared and thermal scanners.
The thermoguard jumpsuit was equipped with an internal cooling unit that maintained an external temperature equal to that of the wearer's environment. This meant that, to infrared and thermal sensors and other devices, the wearer was virtually invisible.
Sources
"Special Ops: The Freelancer" — Star Wars Gamer 6 (First mentioned)