Thermochromic Level Indicator

A housing comprising

• a wall presenting an interior space capable of retaining matter at a first level within the wall;
• means for permitting the matter to exit from within the wall or enter into the wall such that the matter assumes a second level;
• the wall supporting a level indicator,
• the level indicator being formed of thermochromic ink,
• the thermochromic ink having a color transition temperature capable of acting as a level indicator by sensing temperature of the matter retained within the wall in an intended environment of use.