Comment by car

Pretty sure that's a UVB flashlight. There's absolutely no way that anyone is selling 255nm UVC that outputs much of anything for more than a few hours for $45.

A good 280nm chip is ~$100 (https://www.ledsupply.com/leds/uv-c-280nm-nichia-ncsu334a-le...), and it gets exponentially harder to produce shorter wavelengths the further down the spectrum you go. 270nm and 265nm chips are getting there, but 255nm is mostly a research area right now.