4W 254nm UVC Replacement Bulb for UV Lamp - Portable Blacklight Bulb with AA Battery Power for Lab, Sterilization & Disinfection - Works with 254nm/365nm UV Lamps - Ideal for Water Purification, Surface Sanitizing & Scientific Research

This is a decent japanese-made uv-b fluorescent tube. At 4 Watts it's definitely not winning any contests for output, but by the smell of ozone after it's been running for half hour or so in the room, I know it's absolutely working. My only complaint is that it takes a good 10 to 15 minutes to actually warm up enough to reach full output intensity.