Make strobe hidden or no one here will buy it.
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I’ve reviewed and tested many flashlights of this type from expensive and cheap brands (Olight, Fenix, Speras, Sofirn, Wurkkos, Cyansky, Klarus) and can tell you what’s good and what isn’t for a light like this one. Without having tested it, here’s what I like:
Compact, 165 mm long ,37 mm head is a sweet spot for a pocketable light
You don’t mention weight, but should be arouns 200-250 grams with battery
Battery should be user accessible and standard, not proprietary or ‘customized’ like Olight uses
Needs a spring for the driver and tailcap-for durability
Should have a standard 1-1.25 inch (25 mm) diameter tube to be compatible with off-shelf weapon mounts
The USB-C port should be tightly sealed and support USB C to C and A to C charging.
Should support 5v 3A charging input
Output: 4000 lumens is nice, but shouldn’t be the focus. Sustained output is much preferable to raw output.
For this type of light, 1000-1100 Lumens regulated output is satisfactory. If you can go higher but keep the tube temps under 60 C even better.
You should be using a constant current regulated buck driver. There’s no excuse to use a direct/linear driver in 2025 on a mainstream light anymore.
The UI: Should be simple and looks like you’re foing something similar to the Olight Warrior X4 with Lo-Hi and Strobe arrangement. This is excellent for this type of flashlight. However, some suggestions:
Should not have mode memory
Even with just a tail switch, max output should be instantly available from ON or OFF. Olight uses a full press on the tail switch for that (Fenix does too on their new TK lights)
Strobe should also be available quickly
If you want a professional test done, reach out to 1Lumen and saod Nick sent you 
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Do you mean “make it more hidden?” (more clicks?)
Currently it’s not in the 2 main modes and requires a ‘double click’, so depending on ones definition it could already be seen as ‘hidden’. (Although most of the time it’s a bit more hidden by an extra step/click by a lot of other manufacturers.)
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Just out of curiousity: does that mean that you always want it to start on max output, or that there’s an option for it to achieve that if wanted/needed? It’s maybe not the (more ‘simple’) option that you have in mind, but several brands use ‘double click’ from ON or OFF for instant acces to Turbo. Is that not quick enough?
I know that it means that Strobe would need to get a different way to be available quickly.
Different question:
You say that Press and Hold from OFF will give you ‘Momentary ON’.
Is that a FULL press and Hold? If so, what will hapen when you release the switch? Will it go back off.
I assume it’s probably a half-press and hold?
The highest output should be available at any time, but not necessarily the first option in the mode set. Most tactical lights with true tactical-duty UIs have a dedicated switch for that where clicking it or long-pressing activates turbo/maximum output.
For this one it sounds like fully pressing and holding activates that mode.
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BLF newbie question: I hit the 20-reply limit in less than a day 
Thanks again - I’ll get back to you all as soon as the cooldown resets!
Hi Kabukimann, thank you so much for your detailed and thoughtful feedback — this kind of response is exactly why we chose to share our first project with the BLF community first 
You’re absolutely right about the driver. For the ST-DT1 Ultra, we’re using a constant current driver with thermal stepdown and a tuned regulation curve. Efficiency and stable output are core concerns for us — especially in a tactical-style light. We’re still fine-tuning the firmware to ensure smooth transitions and sustainable medium output.
Your suggestion of having 3 brightness levels + Turbo is spot on — and aligns well with what several others have asked for too. We’re now testing a layout with:
- Low: ~250lm
- Medium: ~1000lm (sustained output target)
- Turbo: 4000lm
- [Optional] Ultra-low (moonlight) mode in hidden UI
We’re also taking your color temperature advice to heart — a 5000K neutral white version is in prototype testing now. And yes: absolutely no green tint — bin selection is crucial, and we’ll avoid any unpleasant shifts.
As for early access — you’re already on our short list
We’ll be setting up a sign-up page for a small early BLF run before the full Kickstarter launch, and you’ll be the first to know when it’s ready.
Thanks again for helping make this light better. Your feedback is already shaping the product’s next iteration!
Thank you very much for your honest and constructive feedback — and you’re absolutely right.
We’ve heard this from several users now, and we agree that:
- Starting on Turbo is too aggressive for general-purpose use
- A third level between Low and Turbo is not just useful — it’s necessary
We’ve now decided to revise the UI to include at least 3 main brightness levels, likely structured as:
- Low: ~250lm
- Medium: ~1000lm (sustainable output)
- Turbo: 4000lm
- (Optional Moonlight: in hidden mode if space allows)
We’re also removing “Turbo as default” and moving to a last-mode memory or low-start UI, depending on user feedback.
This is exactly why we’re sharing the project early — to build something together with enthusiasts like you.
Thanks again for helping shape this light. Your comment made a real impact!
Thank you very much — this is incredibly valuable input, and we absolutely take your concerns seriously.
You’re not alone — we’ve now received multiple suggestions in favor of:
- Click ON / Click OFF (not long-press ON/OFF)
- No Turbo on startup
- Press & Hold to cycle modes (Low → Med → High)
- Hidden Turbo via double-tap
- Optional Moonlight from OFF via press & hold
We’ve already begun revising the UI logic to reflect this, and your suggestion matches exactly what we’re aiming to implement for the next firmware.
Our goal is to make the light intuitive, safe, and enthusiast-friendly — and that starts with listening to the community. Thank you again for helping us get this right.
3 Thanks
Absolutely — yes, we do plan to ship internationally!
We’re working with fulfillment partners that can support global shipping, and will clearly list the available regions when the campaign goes live.
You’re already on our early access list, and we’ll make sure you’re notified as soon as it’s ready. Thanks so much for the support!
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Absolutely — we 100% agree.
Strobe will be hidden behind a triple-click (from ON or OFF), and it will not interfere with regular mode switching at all.
No accidental strobe — promise.
We’ve already updated our UI plan accordingly based on community feedback. Thank you for pointing it out!
3 Thanks
Thank you so much for this incredibly detailed and practical feedback — this is honestly the kind of advice we were hoping to receive by coming to BLF early.
Your points about structural durability, thermal control, charging standards, and driver architecture are all spot on. We’re currently using a 25mm tube for compatibility with standard weapon mounts, and we agree: springs on both driver and tail are non-negotiable.
For the driver, we’re finalizing a constant-current buck driver , with a target of sustained ~1000–1200 lumens at <60°C body temp — your benchmark matches ours almost perfectly.
Your comment about USB-C (both A to C and C to C) was particularly helpful, as the first generation is set up as a tactical flashlight, we are not doing USB-C direct charging at this time, and are set up to use the USB-C function directly on the battery.
As for the UI — we’ve taken all this in:
- No mode memory
- Full click = Turbo from ON/OFF
- Lo→Hi cycle (hold)
- Triple tap for Strobe (hidden but fast-access)
And thank you for mentioning Nick and 1Lumen — we’ll definitely reach out to them for a professional review and testing.
Again, sincerely grateful for your input. We’re building this together with the community, and your feedback is already helping us refine it.
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I think to do that, you might need an electronic switch (a.k.a. an e-switch) or perhaps a forward clicky switch.
I prefer e-switches to mechanical switches, but an e-switch is tougher to accomplish as a tail switch.
They’re much easier to do as a side switch. 
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Maybe I’m swimming against the current, but from the early days I fell into the rabbit hole, I remember that most of the tactical lights were designed to stop the perpetrator. That meant: instant full blast. The lights I still have from that era go: high - low - strobe. Where low equals today’s low-medium. Certainly not moonlight.
Today’s light are much more powerfull, so I can imagine something like: full blast - max sustainable - low. But you could consult a few LEO’s about the order (turbo first or turbo last).
Thank you — this is a very valid and important perspective.
You’re right: the core of a tactical light is to deliver immediate, overwhelming output when needed — and that’s something we absolutely want to preserve.
We’re currently exploring two UI profiles:
- One tailored for everyday carry (more levels, soft start, hidden strobe)
- One for true tactical use: instant Turbo, then step down if needed (as you described: High → Sustained → Low)
You’re also right that modern output levels are on another level compared to older lights — so we’re factoring in thermal limits and sustainability too.
We’ll definitely be talking with a few LEOs and military users before we finalize the default UI — your comment is already helping steer that process.
Thanks again for keeping that “original purpose” of tactical lights in focus 
That’s a great observation — and yes, switching between UI modes typically does require either an e-switch or a forward clicky setup.
We’re currently using a mechanical tail switch for durability and tactical feedback, but we’re definitely exploring a secondary e-switch in future versions, possibly side-mounted, to allow deeper UI customization and simpler access to hidden functions.
For now, we’re aiming to keep things clean, reliable, and single-hand usable — but your point about long-term expandability with an e-switch is spot on.
Thanks for your insight as always!
How do you “hold” with a mechanical reverse clicky switch?
And how does the flashlight know that you are “holding”?
As far as I can tell, you can either click or half-click.
When the light is on, just press and hold the button and the brightness will cycle:
Low → Medium → High → (back to low…) – release the button when you’ve reached your desired brightness.
But this feature is generally best suited for electronic switches, especially side switches.
Currently we use a mechanical tail switch, which we simulate with a short press – but for future models with side switches we plan to fully support the “press and hold to cycle” action.
Thanks for your attention to UI detail!
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Okay, thank you for that explanation! 
4000lm is going to require a large amount of current.
That’s going to require a robust mechanical switch to handle that much current over time.