I would also be interested in this. A D1K, if you will. D4K diameter head (obviously it will need to be deeper to fit a reflector) but with all the emitter options from D1V2.
Honestly I feel like Hank could have updated ALL the 18650 side-switch lights (D4V2, DT8, D1V2, DW4) with the new wider head diameter, then added a new 18650 tube to fit the new head design.
Right now it wouldn’t make sense though from a manufacturing/business standpoint, considering he’s already invested into the 22mm tube system for the most recent lights
I wish the 21700 lights had standardized threads, so the tubes between DM11, K1, D4K were interchangeable.
I think the DK4 highlights how chunky the D4V2 is. Don’t get me wrong, I like it a lot, but frankly it’s too big for me to comfortably pocket carry.
I’m sure other people have had this idea, but I’d like to see Hank make a compact 18xxx light as a triple instead of a quad.
Here’s a modded Wowtac A6 triple compared to a D4V2. It might be hard to imagine with the pic, but there’s a huge difference in pocket-ability.
This looks awesome.
I’m overwhelmed by the emitter choices…
Would be nice if there was a good writeup of characteristics to expect with each one, and maybe even comparative qualities (why one might choose 1 LED over another while still very similar in output/efficiency). Is there a page floating about somewhere in this long thread that takes a good stab at it?
Yes, I would be interested in that too.
From the emitter list I am familiar with the 365nm leds, so I immediately bough a D4v2 with 8 5W uv leds 
But I would like to get 2 more D4v2 lights with regular high CRI leds like Nichia 219, and not sure which one to choose because there are so many new leds.
The new D4k, how larger is it compared to D4v2?
I found the following reddit threads helpful for helping me pick, it’s not a comprehensive list but it’s most of them:
Niceee
So best option looks like it is a Dual channel Emisar D4v2 with W1 + 519 4500K
There is no best as such, it’s always a compromise, that’s why all the other options exist (and are frequently ordered) in the first place.
True. But if you want both good throw as a search light, and nice flood for when you want to light up a big area closely, I think those are the best options.
Question regarding dual channels: does ramping work the same with dual channel lights? I mean, can I still have low to high lumen ramp for just 1 channel that I choose?
Will the KR4 be upgraded to 21700?
Yes, brightness ramp works just as expected (1H), the channel mix is set with 3H (it replaces momentary turbo).
This would be awesome… A compact sub-50g triple to beat FW3A / FW3X. 14500 lights are intresting also, but IMO it trades a lot of runtime/heat management for size.
Am I wrong when I say lh351d is a better flooder than 519a? I like the tint better with 519a but I’ve heard it’s not as wide/flood as the lh351d.
519A is still pretty floody, and has a better tint and higher CRI than the LH351D, but with less output. In lights with TIR optics, there will be a very wide spill beam for all emitters. However floodier emitters will have a brighter spill beam and less bright hotspot.
Hank, do you offer D4K as mule with 16x E17A 1800K or E21A 2000K? If so, would a boost driver make sense, too? Hoping for a positive reply.
Also hoping for a xhp70.3 D4K, mule or shallow op…