The 13-watt bulb is truly compact and has a brighter spectrum of light versus other wattages and CFL I have tried so far. My initial order had a bulb D.O.A. but Chewy customer service was quick to help solve the problem.
Got this for my Russian Tortoise, it lasted for 1 year & 4 months. It was used during daylight hours & a red light was used during the night.
Coiled bulbs like this will BURN your animal! Don't ever use!