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Nice to see post has become more active. Nice inputs which could help me later on. With regards to optics does it have to be a specific size (diameter and height)? You can try also yajiamei optics for more options.

My experience with optics is that its best if you get a few different types and see for yourself the beam it produces and choose what you like or need. Optics designed for XML works for any 5050 or 3535 leds with 3535 leds producing a tighter beam. Personally I prefer beaded optics to produce nice beam with no artifacts. Clear tight optics gets you more throw but many times produce artifacts on the edges. For my caving lights I like the beam produced by 60° beaded combined with 20° beaded optics. 60° beaded + 20° clear also looks ok for me if more throw is needed.

I have a few 17mm and 20mm Yajiamei and a few more coming and I can test them if you like. I know I have some output and beam distance stats somewhere written I’ll try to look for them.