Lens Warmer, USB Dew Heater Strip for Telescope Camera Lens with 3-Gear Temperature Controller, Anti-Fog Condensation Prevention for Astrophotography, DSLR, Finder Scope, Eyepieces up to 4.3 Inch

Works as expected, keeps dew from forming on lens.

alright, this is used for 2 inch eye pieces on a telescope and my canon lenses. For anyone who has used the telescopes at night, or done photography in cold weather, you know that foggy or misty lense.......drives you to drink!! This will be a bit big for the smaller eye pieces, but the 2 incher's are just fine. For 90% of standard lenses you will be good also. For me, the usb power supply meshes very well with the adapter I have that turns my Dewalt 20v batteries, into power sources for these warmers. And they work!!! If they can handle the Michigan Winters, they should be able to handle most of what can be thrown at them. Power draw is moderate, allowing me to power 2 of these, from a 5h battery, for several nights, viewing 3-5 hours per night. For me, this is a no-brainer

This lens warmer definitely gets the job done but I wish there was an indicator light to show when it's powered on. This is more of an issue on my end, but I have a rather small USB battery bank I take with me so the warmer works great when it has enough juice but went the battery gets low it warms less and less until it doesn't do anything anymore. It would be nice it have an indicator to see if its still running.I've got a 80mm cassegrain that would fog over in about 15 minutes if not for the warmer. With my tiny power bank I can get like 45 minutes before having to worry about that.

Keeps my camera lens from dewing up even in very humid conditions.

It keep my lens warm and avoid condensation for whole night where the outdoor environment is wet, windy and temperature around 5 degree of celcius.

Generated no heat. Does not draw power. Did not try to use before return window closed.

This dew heater works like a charm! Very nice build material and heat response is fast and consistent. I also wanted to mention the following: After reporting not-working dew heater, they approached me directly and wanted to correct the situation. They did some above and beyond stuff in problem solving, and I am grateful. Top suggestion!

The 3 settings are great when running on batteries, you can use as little power as needed to increase battery life.