The 75% humidity packs are refills for the Tone Protector Cap and Tray. 75% is ideal for more humid climates. Store unused packs in the resealable package that it comes in.  
 
Features of the 2-Way Humidity Packs:
One humidity pack 75% 8g pack
2-way humidity control
Non-toxic
No mess
Individual pack dimensions: 2.75" x 2.75"