Each size 320 Boveda Humidipak = Five (5) Size 64. More power for larger humidors. Lasts 2X longer in smaller humidors. Restore and maintain cigars to a precise Relative Humidity (RH) with Boveda, the global leader in 2-way humidity control. This pack will maintain the right RH for a wood humidor for 2-4 months and an airtight humidor for 6-9 months.