WHY THIS BOVEDA: 72% RH is for premiums in humidifier boxes made from porous materials, like wood or leather. This slightly higher RH is good if you live in low humidity or high altitudes. Use one 5.25"x3.5" humidifier packet for every 25 TOTAL items your humidifier box can hold. NATURAL INGREDIENTS. Trusted by over 3 million people to protect & maintain items at the perfect humidity level. WE GUA Condition: Fulfilled by Amazon | ASIN: B004LHQEOY