The Humidity Indicator Card(HIC) is a kind of visible card. Each
dot on the card points one specical relative humidity degree. The
dot color will change along with the RH degree from blue to pink
(common cobalt-containing HIC) or broown to green (cobalt-free
HIC). This changing helps decide the inside RH degree and confirm
whether the desiccant should be replaced or not. Special
specification can be customized.