Digital Thermometer & Hygrometer Round Mini Size Because it's very small, it can fit inside a guitar case. The accuracy isn't extremely precise, but it's useful as a daily guide. *Replace the battery when the LCD becomes dim. Size: (approx.) Width 4cm x Thickness 1.5cm Power: Button battery LR44 x 1 (battery included) A "hygrometer" is essential for guitar storage. The ideal humidity for guitar storage is said to be around 50%. Famous guitar brands, mainly made in North America, are produced in lower humidity environments. Maintaining the same condition in the high-temperature and humid environment of Asia is very difficult. In Japan, humidity changes along with temperature throughout the year. It varies depending on your living environment, but Average annual humidity: Sapporo: 69% Tokyo: 62% Naha: 74% Annual maximum humidity: Sapporo: 75% (July) Tokyo: 70% (July) Naha: 85% (August) Annual minimum humidity: Sapporo: 60% (April) Tokyo: 45% (January) Naha: 65% (December) These are the figures. Are the values in the room, warehouse, etc., where you are currently storing your guitar, the same as these? By actually seeing the numbers and measuring the "standard," you should adjust the humidity to be as close to 50% as possible using air conditioners, dehumidifiers, dry cleaners, dehumidifying agents, etc. Many people think, "It's okay because I put a dehumidifying agent in the case," without measuring anything, and are surprised when they bring their guitars in for repair. Place a hygrometer near where you keep your guitar, inside the case, etc., and check how much the humidity changes throughout the year. Also, check how the condition of your guitar changes in response to those changes.