Boveda Cigar Humidity Packets monitor ambient humidity by adding or removing moisture to maintain the RH engineered into the pack to an accuracy of +/- 1%. Will not humidify beyond the specified RH, it’s impossible to use “too much”. Reverse osmosis inhibits the passage of impurities, ensuring that only clean, pure water-vapor passes through the membrane into your humidor. Maintenance free, no need to monitor or refill. Each packet lasts for 2-4 months before needing to be replaced; you'll know when it is time to swap the old one out because the filling will have turned into a solid wafer.

(NOTE: These are sold one individual packet at a time, product photos use the boxes because they very prominently show the humidity control percentage for illustrative purposes.)