Reversible Humidity Indicator Card is designed for use in the semiconductor and electronics industry. As the humidity increases, the chemically impregnated spots change from a blue color (DRY), through a lavender, to a pink color (HUMID). As the humidity decreases, the spots change from a pink color (HUMID), through a lavender, back to a blue color (DRY). Each of these cards is accurate to ±5% relative humidity (RH) at 75°F (24°C). Other humidity combinations are available by special order.