I ordered the 3000k one, I like warm throwers. Also since we don’t know the bin and cri, I assumed 3000K would render reds and brown better than the 4000k one.
After initially selecting 4000K, I switched to 3000 because I have yet to try a thrower that warm. I suspect it’ll end up swapped to 4000K because I have those in 80 CRI (and on another continent, to be picked up when travel is a thing, in 90 CRI).
Very curious on how the xhp35 is in 3000k in this light. Please share your impressions when you receive it 
Sbt90.2 looks amazing with regards to what it can do on turbo.
Any idea when the E21A version of the KR4 will be available? I want to order them together to minimize packages.
Just curious, is the K1 head diameter bigger than the FT03S head diameter?
If so, then the K1 with SBT90.2 should possibly out-throw the FT03S with SBT90.2?
It’s hard to say, our E21A LED package is stuck on the way for 2 weeks, no one can tell when it will move again.
Slightly, but the quality of the K1 will be much bettter and very competitive priced
Just ordered, thanks again Hank 
Nope, been waiting for XHP35 for a while and ordered one in 4000K as soon as it was available. I have a couple lights with SBT90.2 but now I’m thinking I might need this one too. Waiting for KR4 E21a as well. My poor wallet…
Since white flat and SBT90 are both intended for use in projectors, there might not be any warmer tints in the works.
You can see the datasheets for example of Oslon Boost HL, there is no warm white for “white flat”.
There are roughly without getting into details, 6500K to 5000K, nothing warmer than that.
And you can easily suspect something at 5000K will be lower brightness than 6500K (as a brightness bin)
As for SBT90.2 you can also look into the datasheets and see 7000K, 6500K and 5700K are the only CCTs available, nothing warmer than that.
Just ordered one.
That one has a boost driver.
It’s the first boost driver I’ve ever gotten to run my code on. I don’t know what the efficiency will be like, but I’m guessing it should be significantly higher than any of the linear drivers currently in use. It probably also opens the door for running LEDs in series, and for mixing LEDs of different types… so I’m hoping to see more like it in smaller lights.
Maybe he could use this boost driver with the E21A KR4.
Oh - just saw the SBT90.2 K1 listing - price is about right in my opinion.
Boost drivers with 2 amp output are relatively easy, inexpensive compared to getting higher amps. This is why the XHP35's are so commonly used. In a 4S LED configuration, same driver would restrict amps to 2 amps per LED. That isn't so bad, just not getting in the 3K to 4K lumens range. Maybe 2.5 amps per LED could be done reasonably, all depends on the parts/driver design.
So, like loneoceans’ lume1?
That is basically a buck driver, you do not need boosting from an LED with a VF of 2.8V-3.1V at 3A when the input voltage is 4.2V, that is buck. And at lower output currents the VF will be even lower than that. By 3V the cell is empty anyway, so all it is doing is bucking for that matter.
Also that 5mm by 2mm inductor cannot do serious boost from 3.6V boosting to 14V of an XHP35 HI at 2A, for that you need some proper sized inductor, not something that tiny.
Hank, any plans on bringing flashing kits to the US warehouse?
I’m afraid there is no such plan, the US warehouse is free shipping, while the reflashing kit is too cheap to provide free shipping. For most of the orders ship from China warehouse to the US, it’s via special airline service (unless the order amount is too small), which take about 2~3 week to the US.
Did anyone notice this?! Unlikely because it was a short window.This is Certainly FAR from a deal breaker. 
Just caught me by surprise.
When the SBT90 first appeared in the drop down box it was $35. Total price for light was $114.
Five minutes later I ordered and the LED went up to $39.99! lol! Total price is $119.90. I was baffled! lol! I knew there was no shipping so I went back to drop down box and noticed the change.
I have always been curious and inquisitive,wanting to know the answers! He probably made a mistake in the first entry or decided to raise it a bit.
Either way it seems like a great light and a fair price. 