This kit contains four aluminium discs each having a different durable finish:
Matt black, mirror black, matt silver and mirror silver.
Bonded to the reverse of each disc is a liquid crystal thermometer measuring 30ºC to 65ºC in 5ºC increments. The liquid crytal device on the disc is easy to read and shows how absorption of heat radiation depends on surface colour and texture.

The discs have a warning sign in the middle which glows up if the temperature at which the discs could be damaged is reached.