SVBONY SV172 Dew Heater, Lens Warmer 240mm, Universal for Telescope Camera

Great product. Works as advertised. Usage depends on your camera, lens and the weather. Ensure you power it up with a good power supply.

An affordable and effective dew heater; I've used this kind before and it works well for my 14mm wide-angle lens. I never set the heat control to High, though. It's warm enough at a lower setting. I run it off a small, portable power bank.

Works well and low power usage

I bought several of these dew heaters for my telescopes and lens, and found them to be very well made, at a great value. They can be fitted snuggly around the tubes/eyepieces and remain fixed in place. Proper sizing [circumference range] for your intended use is critical, so make sure you purchase the correct size for your application [as they don't stretch (and shouldn't)] As a test, I tried strapping two units in-line to wrap a larger telescope tube and they worked great... just requires 2 USB ports. The included switch/temperature control is compact and very easy to operate. The nice little padded mesh travel/storage bags are a nice benefit too. I was skeptical that these 5v USB powered (vs typical 12v powered units), devices would be able to provide enough 'heat power' to defeat dew onset, but they work very well; and their quick/convenient USB plugs makes hookup (into 60W USB charging hub) quick -n- easy. They need just a bit more time to heat up as compared to older style 12v [higher amps] strip heaters, but they get the job done. Their value to benefit and build quailty is terrific, and I suspect that I should get multiple years use out of them.

Purchased this for my 80ED. Works perfectly fine, another quality product from SVBony. I have yet to be disappointed by these guys.