Reddit reviews Thousand Oaks Four-Channel Digital Dew Heater Control Unit - Requires Heater Band/s.

Here is the full album including the narrowband channels

• Red zone for light pollution (this is a narrowband filtered image, so no fucks given)
  
• Orion ED80T CF
  
• Stock focuser replaced with MoonLiteFocuser + High Res Stepper Motor w/ MoonLite Mini V2 Controller
  
• Orion Atlas Pro EQ Mount
  
• STF-8300M CCD - FW5 -20c Temperature
  
• Astrodon 3nm HA - Here is a topic I made comparing the 3nm HA Astrodon filter to a 7nm HA Baader filter
  
• Orion Field Flattener for Short Refractors
  
• TheSkyX Pro with Camera-Addon for image acquisition and automation
  
• PemPro v2 for getting an accurate drift align (drift aligned explained here)
  
• 10 x 15 minute dark exposures at -15c
  
• 30 x 10 minute Hydrogen Alpha sub exposures
  
• 20 x 10 minute SII & OIII
  
• 20 flat frames using Spike-aTM Flat Fielder
  
• 50 bias frames
  
• 2 pixel dithering
  
• SBIG ST-i CCD for auto-guiding using OAG-8300
  
• Pixinsight for basic histogram stretch and curves adjustment - They have a Free Trial, use it!
  
• Dew Heater with heater band

Dew heater straps. They're basically cloth straps wrapped around nichrome wire. You need the strap and the controller.

Lots of examples on the market those are just the first to pop up on amazon.

Edit: They might be called dew straps/strips/bands ect. but they're all the same thing.