Hey there, 7histology! What's best depends a lot on the task at hand.
What do you intend to use the UV output for?
A lot of the time, the purpose drives the spectrum selection and hence the light/flashlight.
Eg. 365nm curing lamp or flashlight for Norland 61 curing, a dermatologist's Wood's lamp (also ~365nm) to diagnose skin ailments, forensic UV to pick up latent fingerprints, UV illumination for UV photography.
As always, do use proper eye protection when using UV emitters.
I have several convoys, don’t waste your money. I have found the Eagtac P200lc2. They have one with a UV emitter. It has some visible light but less than any others that I have found. It is a 3W led and uses 18650 batteries.
Looks like we have a new contestant entering the fold. Nitecore just announced four 'Gem' lights designed to be used to check the internal structure of gem stones, especially jade. Two of them are UV lights at 365nm and 3000mW. The GemUV8 has a small aperture with the LED fastened directly to the bottom of the lens, while the GemUV10 has a larger beam so it can illuminate a larger area. All of the Gem lights can use either an 18650/RCR123 or a primary CR123A.
Right now the Nitecore Store is listing them at $59.95.