Here are some first impressions based upon putting a couple of them together, but not installing them in a keyboard yet.
First, these are the components for the switch that I received in the mail:
-U4 Silent Tactile Stem
-“Pearl White” switch top [no slot / no LED]
-“Pearl White” switch base [linear / tactile leaf]
-62 gr Korean spring
-PTFE Lube Blend for springs
We have to remember that the Boba is envisioned as a modular switch.
I ordered the “no slot” top, as it is said to most greatly reduce wobble. It precludes the use of LEDs in that location, but that’s not the priority here.
My first thought upon putting one together is that these switches have relatively tight tolerances. Which is expected, since I’m using the “tight tops.” The parts fit together great, but there’s not as much “give” as some other switches. It’s not “loosey goosey.”
I had to push firmly to ensure that the top and bottom housings were properly mated. I experienced the same thing with the older Sky tactile housings.
Switch-Feel:
I can see why it is described as a “D” shaped profile. If the Silent Forest is represented by a “P” shape, it which there is a definite but perfunctory ‘bump’ at the top of the keypress, followed by almost linear travel, the U4 is better described as a “D” shape.
There is almost no pre-travel at all, probably less than Aqua Zilents, although I’d have to check. The stem does not protrude above the housing as some silenced MX tactiles do. Maybe ever-so-slightly, but it is almost imperceptible. A hair’s width.
So when you do press down, you are met immediately by tactile resistance. The resistance immediately ramps up, and does not taper down until the very bottom of the key-press. So it is a “D” shape, and the non-tactile portion of the keypress is almost non-existent.
The level of tactility reminds me of a T1. It’s not the same tactility, but the intensity is similar. It’s not wildly different from pressing down on the stock 65G T1s on my hotswap board. Definitely a greater intensity than most of the Ergo Clears I have tested. But I think Zilents are more tactile, sharper, and offer greater resistance. This could be a good or bad thing, depending on your preferences.
Whomever said that 62G springs were not enough for the U4 stem, I don’t know what they were talking about. The stem rebounds forcefully, and energetically. The springs remind me of 62 gr Spirits, maybe the Spirits are a little stiffer. It’s MX Blue-like. The fact that these springs rebound so heartily gives me confidence that the 55 gr Spirits I have might work. I’ll test the 45 gr as well.
Anyway, this is a lot of text to describe only assembling two switches. I will assemble more and try to use them. I will try 55 and 45 gr weights. Then, I would like to test the Halo stems, Silent Forest stems, and regular OUTEMU Sky stems. Maybe I’ll pull some stems out of MX Clears as well.
Other notes:
There is indeed a ‘Tao’ symbol on the housing underside, as described in reviews. The OUTEMU label is clearly etched into the bottom [the top housing reads “GAZZEW”]
The housings themselves are semi-translucent. When I press downwards, it is possible to see the white stem bottoming-out.