Accuracy-accurate to within . The hourglass is fixed in place with high-temperature adhesive and small metal fasteners. The sand timer is suitable for use in the sauna room, allowing you to monitor the fixed time interval of 15 minutes. 15 minutes-the popular length of time to enjoy sauna. It also includes 5-minute and 10-minute approximate markers for shorter sessions. Just use the 2 screws provided to install it . Wall-mounted Align the additional wooden mounting strip vertically, screw it into the pre-drilled hole, and hide the mounting strip perfectly behind the hourglass machine. It is best to install the timer opposite the heater and control it by simply rotating it. Even if it is used for a long time, the accuracy of the watch remains unchanged because of the uniform granularity of the annealed and screened sand.