SVBONY Lens Heater Warmer Dew Heater Strip for Telescopes and Camera Lens 240(D:76mm)/320(D:102mm)/400mm(D:127mm) SV172
Dew Heater
USB Lens Warmer, Lens Dew Heater Strip with Temperature Regulator, Condensation Prevention for Telescopes Camera DSLR Lens Telescope Eyepieces Less Than 3.15 inch (80mm) in Diameter : Amazon.ca: Electronics
Where to put a dew heater on Refractor (Dew shield or Body) - Refractors - Cloudy Nights
Dew Heaters for Astrophotography - Keep Your Telescope or Lens Dry