The Lockdown Hygrometer Gauge helps you to monitor the humidity which is critical to preserving the condition of your firearms. The Lockdown Hygrometer provides accurate relative humidity readings at a glance. Excessive moisture in a vault or storage area can cause rapid corrosion and pitting on metal surfaces. It is important to monitor and control the relative humidity in your storage area to be sure your guns are protected. This hygrometer gauge mounts easily with the included fastener and/or hook & loop and is easy to read with large numbers.