You should, the zwb2 filter is really a game changer.
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With the zwb2 filter, does it make much difference which UV LED is behind it? I’m reading that Nichia UV LED doesn’t ‘leak’ much visible light even without a filter. But with the filter, are some other, brighter LEDs better option?
If you trawl through AliExpress listings, you’ll find something that fits. Possibly more options will be available once CNY is over.
Absolutely agree on the benefits of a ZBW2 filter, removes vast majority of that annoying grey-blue visible light.
I’d persevere with finding a filter, unless you’ve a reason to have multiple 365nm lights 
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I think I spend an hour yesterday browsing for a suitable ZWB2 filter on AliExpress and found loads of different sizes, but the closest sizes I could (easily) find, were all 18 or 20mm. I measured and 18mm would be to small, because the hole in the front of the bezel is 18,5mm and max. diameter on the inside (past the threads) is just a bit under 20mm, so if 20mm is indeed (exactly) 20mm, then I won’t be able get it in probably.
But I have to place an order at Convoy/Simon anyway, so I will order a 20,5mm filter (Simon has a really good/competitive price on those!) anyway and give (gently) sanding/grinding it down a chance. At worst I lose ~ € 2,50, so there are worse things than that.
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It would make an interesting comparison, however, it would be very difficult to measure as dedicated UV meters are expensive, and you’d also have to have some sort of way of measuring the “leaked” visible light- regular lux meters probably sensitive to UV so you’d get an overestimate of visible light lumens.
Ultimately the decision will be based on your intended use/requirements:
The ZWB2 filter isn’t perfect, it lets through a small amount of visible light- you can find transmissivity graphs online. It passes around 10% at 400nm, which is likely visible. When combined with a “good” UV LED which doesn’t have much visible light, this is close to unobservable.
The more narrowband LEDs are often more expensive. If you need “more” UV light, and can live with a little visible light, then the logical choice is to go with a big Chinese UV 365nm LED.
I’ve not seen a spectra comparison of all available 365nm LEDs, it would be interesting to see which have the “purest” output.
I found this neat visual comparison of 3 UV LEDs with and without filter:
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It is maybe not directly showing students that UV is invisible, but it might be an interesting ‘experiment’ to show them. I used the only UV light that I currently have (Sofirn SP31 UV), which doesn’t have a ZWB2 filter, so there is extra/excess visible blue light, but for this experiment it didn’t really matter.
I used a pair of (quality) clear safety glasses, which are rated as UV400 glasses. First I took a photo without the glasses, in which the paper (with highlight marker stripes) light up clearly by the UV light.
Then I put the UV blocking safety glasses in front of the flashlight, which than clearly showed that basicly all the (UV) light was blocked.
You can probably also do this with sunglasses (or regular glasses) which have an UV rating, but with clear safety glasses it’s probably the most obvious that they don’t interfere or affect the regular visible light.
Not sure if it is something that is usefull or interesting to show your students, but it is something that just popped into my mind! 
I took 2 sets of photos, because it wasn’t possible (for my phone’s camera) to expose correctly for everything in one shot. In real life it is way more clear, since your eyes can correctly expose for the scene as a whole. (EDIT: in a different topic djozz found a way so that his phone’s camera exposed properly for the UV, but I hadn’t thought of that unfortunately.)
Manually corrected the camera settings to compensate for the UV hotspot on the paper:
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1Lumen review of UV lights (with and without filters):
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If it’s the one I’m thinking of, and I haven’t seen any exceptions to this rule, what “little” it does leak, is an eerie ghostly greenish color that’s more annoying than “leaky” 395nm emitters, which at least “leak” purple.
I heard people going off that these low-leak 365nm emitters don’t need filters, but they absolutely do, maybe moreso than 395s.
I got the SFwhatever that has the 19.5mm glass, and while it’s nice and throwy, I rarely even touch it anymore because of that glow. I didn’t really mind at first, but when you’re aiming at stuff that doesn’t fluoresce, it’s like shining a regular light on low. Only when it hits something that fluoresces does the thing really light up, but that glow is always there.
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Great find! I wasn’t aware of that thread, I do remember djozz UV output tests using the fluorescence of uranium glass to convert UV into measurable wavelengths - genius!
This is also a great idea, I use this method to verify safety specs actually block UV before I wear them…!
I like the concept that different materials have different transmissivity at different wavelengths (example, ZWB2 filter, plastic glasses, etc). Would be a deep rabbit hole to go down with different coloured LEDS and filters
This part of your post somehow reminded me of a video I recently saw about UV detection cards. Several light/UV sources are used and also a few safety glasses are checked for UV protection.
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Too bad, I Edit: AE, the system, the vendor, will not allow shipment to the US…
Sorry re: the typo… If it were up to me… I say, ship away…
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Awww, be nice and allow it, k?
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He shipped both together for me, just said I had to install the filter myself.
The S2+ was a gift for someone else I was dropshipping it to, so I had to send them a link on how to install it. Disassembling their first enthusiast light on day 1, heh.
I got both in the same package, but I had to contact Simon and ask him to do it. The system wanted to separate them.
Sorry, Im not from US, just knew this was original convoy flashlight store, made the assumption its universal.
No problem. Good catch. Good deal. I was going to buy one… or maybe two. I didn’t find out until I went to buy one and was told it couldn’t ship to my address…
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An ignorant questions about batteries for UV lights.
I was looking at Convoy S2 UV or T2 UV. They don’t have built-in USB chargers, correct? But would T2 for instance work on AA alkaline and what are the consequences of doing that? What are the runtimes and is the output regulated somewhat?
Cheers!
I did a quick search and it seems that the T2 UV will run on AA cells.
You will get less ultimate brightness and less runtime. But it may work OK, depending on what you need to do with it.
Do you use NiMh (example Eneloop) cells for anything else? they would be much better than Alkaleek AAs. If you do use them, you must have a charger… Or maybe pick up a cheap charger that takes 14500s and a couple of them. I have seen the little single bay chargers that take USB C input for under $10. 14500s under $5 per. So for under $20 you would be set.
Or buy a TS10 with battery and charger for around $15 … like getting the TS10 for free. Of course, you probaly want a couple of spare 14500s… Yeah, more of the old rabbit hole… SIGH. 
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I found Sofirn SF16-UV on Lazada (Thai/Chinese Amazon of sorts, but without duties) for 1000 THB with a battery included.
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