Thank you! It takes quite some efforts to reduce the 20mm board to make it fit into the S2+. I thought maybe there are better hosts out there that fit both a 20mm board and a 10507 carclo lens. I didn’t consider yet that some TIR lenses won’t let UV radiation pass through. What lenses would be appropriate? Actually, I planned to attach a ZWB2 bandpass filter to block the visual spectrum of the light. Another plan is to build a triple Nichia UV or triple Viosys UV with 10507 lens and parallel board.