Most guitar cases are made of twice as much wood as the actual guitars they hold. Boveda has some catch-up work to do, so your first Boveda won't last as long as subsequent ones. We recommend seasoning your guitar case first for best results. HOW TO SEASON YOUR GUITAR CASE
*Do not mix different Boveda RH levels within the same guitar case. Instead of creating a new "average" RH, the moisture will merely transfer back and forth between the Boveda. Do not use Boveda with other humidification products. They will fight against each other and reduce the efficiency of the Boveda.