This product works great. Heats up the ambient temperature in the night for my Crested Geckos to a nice temperature. I used it last night since I got it and already the Geckos were basking under the heat. I highly recommend it for Cresties!
I keep two of these 40watt ceramic bulbs running over top my 20gallon long tank (I use the Nano Combo Dome) and it keeps the warm side at 82°-85°. Both my snake tanks are set up like this and my guys love it! No bright lights!