Your guitar is special. So give it some respect. The boveda humidity control guitar storage 4 pack is everything you need to store your instruments properly. Whether youre an electric acoustic or folk instrument player each pack defends against fluctuations in humidity providing a stable environment between 45 55 rh. Youll never have to worry about warping cracks and shrinkages damaging your guitar. A worlds first. Boveda humidity control works like no other humidifier available. Using its patented two way design each pack removes or adds moisture as necessary preventing volatile changes inside your instrument case. That means worry free storage no matter where you are. No mess. No hassle. No worries. Each boveda is ready to go straight out of the box. Consisting of a specially saturated solution of pure water and natural salts all you have to do is put it in your case. Its that simple.