the COB uv leds are much cleaner UV, in a normally lit room you can barely see the light blob where you aim them until you hit something that fluoresces. Also the lasers are pretty pure, from what i've seen personally.

But anything in the portion of UV that makes ozone doesn't get anywhere near that small - the smallest is about the same volume as a AA battery, just more squat (larger radius), and they require AC voltage, and none of the ones i got lasted very long, i imagine my AC supply didn't have enough current. they use ~18V iirc? maybe 10V, i don't remember. it's low voltage, though.