Planet Waves PW-GH-HTS - humidity sensor with air moisturiser. Suitable for steel and nylon string acoustic guitars. Flat sensor for use inside a guitar case, can be clipped inside the guitar (fixed by the strings).

Planet Waves PW-HPK-01 Humidipak - automatic humidity control, 45% RH. Includes headstock pouch, soundhole pouch, gives 2-4 months of use after opening, depending on temperature and air humidity (see instructions),...