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).
A few years ago I bought my first really good acoustic, a Gibson J185 True Vintage, an amazing guitar & pretty expensive & so I decided from the beginning to look after it properly & that meant keeping it humidified during the winter months when the air in the house dries out with the central heating on constantly. After doing a lot of research and reading some horror stories of certain brands of humidifiers leaking liquid into some very expensive guitars I chose to go with the Planet Waves HPK-01 Humidipak system which is or (was) (not sure) endorsed by Taylor Guitars which was good enough for me. I found the HPK-01 system to be excellent & was quite frankly amazed at how well it performed, but as time went by some of those horror stories of leaks destroying guitars I'd read began to play on my mind. I must stress that none of these stories involved the Planet waves HPK-01 system & I have never heard of anyone ever having any kind of problem with that product but the HPK-01 does work by suspending a pouch of a liquid gel type substance that absorbs & releases moisture when required in order to maintain a steady relative humidity level inside the sound hole & eventually the worry, unfounded as it probably was ( I'm sure I'm not alone here) became too much & so I needed to look for something else that didn't involve liquid. I found a lot of products available which utilise sponges to lock in a minimum amount of water making it safely available for humidification but many of them especially some of the snake types had hard parts which could potentially damage the delicate nitro finish of my guitar... Then I found the Planet Waves PW-GH-HTS system which includes a fairly accurate humidity sensor & a sound hole humidifier which utilises the sponge idea & hangs in your guitar sound hole suspended by the strings with no hard parts coming in contact with your guitars finish. Used in conjunction with the PW-SIH-01 small instrument humidifier as a replacement for the headstock compartment pouch of the Humidipak system this is a fantastic product, the only downside is you don't have the ability to absorb moisture when the RH gets too high that you have built into the Humidipak system, & obviously you must monitor the humidity & wet the sponge when required, but on the plus side you get 110% peace of mind. No more worrying! Great product