Humidity Indicator Card (HIC) is a kind of visible card. Each circle on the card shows one special relative humidity degree. The chemical reagent is dripped into the circle. Its color will change along with the RH degree from blue to pink (common cobalt-containing HIC) or brown to azure (cobalt-free HIC) or yellow to green (cobalt-free HIC). The color change helps users decide the inside RH degree and confirm whether the desiccant inside should be replaced or not. Special specification can be customized. Our standard HIC types are 5-10-60%, 30-40-50%, six circles 10-60% and so on.