UVB is quite a range of spectrum and there are currently no LEDs that produce it well or for long - they burn out quick. UVB can damage plants or can improve cannabinoid profile depending on use. The addition of trichomes via UVB is a common statement made by people that use it, I found no evidence to support this. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.