The dew heater is placed on the optical tube to prevent optics dewing. A very common problem especially in winter and in sealed optical tubes, such as refractors or Schmidt-Cassegrain. These dew heaters, 12 V powered, heat the telescope preventing the formation of condensation on the optics.
This dew heater can be easily installed thanks to Velcro which ensures a strong and uniform fixing. Thanks to elastic fix, it can be installed on from a small range above and below the specified diameter.