I measured it with a digital caliper. The caliper reads exactly 5mm, though it’s not perfectly accurate so it might actually be 5.1mm.
The other reason can be that the stock LEDs are actually 4.8mm. The “5mm” LED family includes both 5mm and 4.8mm (usually the straw hats).
Ah, ok. Since it’s copper, I should be able to work the opening a little wider.
Ah, looks like the logistics has really shat the bed.
The mail man never arrived today 
Let the fun begin!
The "5800k" (5500k?) has landed. You decide for yourself if it's actually 5500k or 5800k. (all pics are taken at 5500k)
Looks nice, would definitely like an order of those!
Nice smooth beam, but there will be people who dislike the slightly greenish edge. Is this a real thing or does it just show up in the pictures?
The greenish edge is quite real, but should be slightly less visible in real life.
What I see also differs from screen to screen. I noticed that the greenish edge is exaggerated when viewed on the phone instead of on the monitor.
seeing the cheap 5mm leds i see in the typical 9 led lights it seems you are correct.
joke is those are henry ford leds.
they can render any color as long as its blue!
it becomes clear just how bad they are when you take 2 harbor freight 9 leds and rplace the leds in 1 with high cri types.
i have a demo pair here to show that.
the ebay high cri make a much larger spot that covered up the stock one like its turned off.
Shipping update:
id30209 – RR278675085TH (1× 5500k)
kame sennin – RR278675071TH (1× 5500k/1× 3400k)
Nismo – RR278675068TH (1× 3400k)
denkiman808 - LX104000012TH (1 x 5500k/ 1 x 3400k)
ludolf - RO247700195TH (1x 3400k)
LowLumens - RR252867131TH (2x 3400k)
AguassissiM - LX104000030TH (1x 5500k/ 1x 3400k)
DavidEF - LX104000043TH (1x 5500k/ 1x 3400k)
tomas_f - RO247700235TH (1x 5500k/ 1x 3400k)
Unheard – RO247700258TH (1× 5500k)
Samples also sent to Djozz in exchange for original Yujis.
Thanks rngwn, received the LEDs in the Netherlands.
Really happy with them 
It is just the cree edition 5mm
^ is that a good or bad thing?
I copied your mod a bit on my granny's headlight ;)
I finally got around to ordering 100 of these unique little 3400K LEDs today!!! Looking forward to working with them on some projects.
Been out of the making and modding lights for a while… but with 2 (…and now looking at 3) PG&E power outages here lately I’ve renewed inspiration to make more custom battery powered indoor lamps and lights.
Lights that run for hours, soft lighting that is warm and comfortable. That’s what is needed when the power is out for many hours! These little warm high CRI wonders have inspired me.
Here's the beam comparisons between "5800k" version of these LEDs vs Original Yuji's 5600k LEDs (Thanks Djozz for sending these to me!). All pics are taken at 5500k white balance setting.
Yuji's: Perpendicular
WTS: perpendicular
Yuji's: beam profile
WTS: beam profile
Tint comparison. Your LED wins for its better beam profile, tint is really close.
Are there any 3mm options in HI CRI?
They don’t make 3mm version regularly. That means I will have to make 10k pcs minimum and I don’t get to choose the tint.
So, that’s a “no” for now.
I got a sample of 10 of his high CRI 5600K leds from rngwn in this week and I did some testing.
First a beamshot from 20cm distance from the wall:
Actually this shot looks nicer as in reality, the beam is indeed really smooth but there is a slight tint change at the very edge but it is nothing serious, at least not so bad as rngwn’s own beamshot in this thread.
The tint, I measured at 5mA and at 50mA.
5mA: CCT=5610K, duv=+0.0033, CRI=98.0, R9=91.4, R12=80
50mA: CCT=5666K, duv=+0.0010, CRI=98.2, R9=92.8, R12=87
Here are some graphs at 50mA:
So the tint is really really good and does not change much at different currents.
The light output. I made no graph (not enough time) but a video. You see the led shining at a luxmeter that I placed at a precise distance so that the luxmeter reading is quite exact 10 times the output in lumen. So a reading of 93 corresponds to 9.3 lumen total output. The voltage and current can be read from the USB power supply. I checked, they are not greatly off from reality.
So, like the 3400K led, it maxes out at about 120mA (25 lumen), but above 80mA (22 lumen) there is not very much gain. This is a very nice performance, at a bit but not much better than the Yuji 5600K led.
Conclusion: great led again! Well done.