They mean a āKR1ā, a single-emitter KR4.
Not a thrower.
Ever since the original D4 came out, people have been asking for a specific type of light which Intl-Outdoor has not yet made ā a single-emitter EDC-style light. Basically, a Noctigon version of something like a ZebraLight SC64 or an Olight S2.
The D4 makes about 4 or 5 cd/lm, while the D1 makes about 33 cd/lm. Between the two is a hole in the product line.
The goal would be to fill that hole with something as small as possible with 18650 and one LED ā narrower and lighter than a D4, with thinner walls. The beam pattern would be about 10 or 12 cd/lm. Ideally, with a deep carry clip which is straight and runs parallel to the body. The body is probably about 21 mm in diameter, the head is as narrow (or almost as narrow) as the body, and the light is ideally under 100 mm in length if possible.
Something like this would work well with a regulated 5A driver. For the LED, it might make sense to use XP-L HI, XP-L HD, LH351D, or 4xE21A / 4xE17A arranged together so the LEDs touch each other.
The choice of optic or reflector probably depends on which LED is used and how throwy it is. For example, XP-L HI might work with a frosted TIR or a heavy orange-peel reflector, while LH351D might work better with a clear TIR or a light orange-peel reflector. It would require some experimentation to produce a nice-looking beam with the right amount of candelas per lumen.
I hope this description clarifies the idea.
More like this for e21a:
:+1:
This is essentially XHP70, XHP50, XHP35 under one single footprint which one can actually solder properly not having headaches with alignment in mass production of 4 different footprints. This is exactly why XHP50 in 3V is used for without wasting so much space with a wide base, time and effort.
And the beam pattern is not better than what those XHP type of LEDs have to offer.
Please for XHP35 Hi 4500K CRI80+ 
This would be a great KR1 option!
I just want to second what ToyKeeper replied to this. What she and I are talking about is not a thrower, but an EDC light thatās more throwy than a D4. It may or may not have more maximum turn-on throw (it probably would using an SST-20), but able to do a given amount of throw (e.g. 5000 candela) with less heat and battery use. My first choice of optic would probably be a textured reflector, which loses a tiny bit of throw for a smoother beam.
The Lumintop FW1A is similar to what weāre describing, but I think Noctigon could do a better job. A slimmer host would be ideal, but the same host with a slightly longer head to accommodate the single optic would work for me.
I see no point in smoothing out a beam intended for max throw. An XPL-HI in a SMO reflector looks great to me - I have many modded XPL-HI V2 5D's and V4 3C's in SMO EDC's, all have a good look'n beam. SST-20's have to be CW/low CRI to get decent throw. The 95+ CRI SST-20's don't throw well.
The point is an all around versatile beam, not maximum throw.
Max throw is not the goal of what I suggested, and given TKās inclusion of the LH351D and clustered E21A quad on her list of suggested emitters while excluding the White Flat and Boost HX, Iām going to assume sheās having a similar thought. The goal is to be a good EDC light thatās balanced. The D4 is very floody. A White Flat in a 20mm reflector is very throwy. Somewhere between those extremes lie most popular EDC lights, like the Zebralight in my pocket as I write this, or the Lumintop FW1A. Hank has never made a light in that class - perhaps itās too ordinary when Hank is often pushing the limits, but Iād buy one.
As for high-CRI SST-20s, I have one in my XinTD C8. Itās not far off what an XP-L HI would do, and the better color rendering helps some objects to stand out against their backgrounds. I could put a Boost HL and a FET driver in that C8 and it would throw a lot farther, but it wouldnāt be more useful to me.
Those of us talking about clustered (almost-touching) E21As are familiar with the Cree XHP series, Nichia 144A, and other single-package multi-die emitters. We still want the clustered E21As.
I think the optimization Clemence came up with was to position them slightly too deep in a throwy optic or reflector. That does lose a bit of throw, but smooths out the beam pattern. People who want clustered E21As will generally be happy with that tradeoff.
Why bother? Because E21As are beautiful. Theyāre prettier than 219Bs, and thatās hard to do.
TIR can be very throwy depending on size and design, Fireflies E01 is a perfect example of this. Parabolic reflectors and TIR optics follow the same physical laws and have the same limitations.
E21A quadtrix model would be an insta-buy for me, itāsā very easy to smooth the beam out with some DC Fix if people are bothered by a donut hole (and with an OP reflector + Hankās talent at reflector design it shouldnāt be that bad anyway).
I ask you to think about the production of a battery accessory for NOCTIGON 4*18650 METEOR M43 and EMISAR D18. To use flat top batteries.
Good idea, thatās actually the Convoy 4x18A flattop adapter, i am using it on my BLF Q8 
Maybe Hank (or Simon) is willing to sell it as replacement part
I would expect the E21A should work fine with a quad Carclo. I donāt know what the throw would be. Carcloās website indicates not much better than a 219C. I would have expected a bigger difference.
I mean version with quadtrix board like Virence makes with the emitters centered in a reflector.
It has already been said, but just to confirmā¦ The idea is to make a general-purpose daily-carry light with a beam which is balanced and beautiful. It is not meant to maximize throw or lumens. It is meant to be small and practical. The beam would ideally be around 10 or 12 cd / lm, with the beam blended well enough that it would not have any sharp edges or a rainbow effect. This could require a frosted lens, frosted optic, or de-focused reflector.
The D4S beam is pretty close to what I have in mind. However, the D4S is 32 to 39 mm in diameter, and Iām hoping for a much smaller light which is more like 21 mm ā basically as small as possible with an unprotected 18650 cell. Also, I would blend its beam a little more because the edges of the D4S hotspot are a bit sharp.
I suggested E17A / E21A because they usually make the most beautiful beam. However, there are other nice options too. I particularly like Nichia 219B, XP-L HI, and XHP35 HI. These are all good at keeping a consistent color throughout the entire beamā¦ unlike rainbow beam LEDs like XP-G3 and XHP50.2.