The box says 'effective' and other reviewers have said they are cold to the touch when in use, but both bulbs I ordered got so hot I couldn't could touch her without getting burned. The bulb itself was way hotter than any other CFL I've come across, but the cartridge with the ballast would peel the skin off because it's so hot. The grow cabinet I tried using them in is adjustable to 85 degrees Fahrenheit, but after a few minutes of operation the temperature rose to over 100 degrees. I hope the seeds I'm trying to germinate haven't been damaged. I think I'll have to try LED bulbs. Update: I had to insulate the lamps and add a fan to dissipate the heat and now it works in my application. It took a lot of work on the hull, but I'm happy with the result. I uploaded a photo of a cabinet with a fan.
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