Gazzew's Boba U4 silences the keystroke without the mush

The Boba U4 silent tactile switch answers a common complaint: most quiet switches feel dead and mushy when you bottom out. Gazzew’s design keeps a strong D-shaped bump with zero pre-travel, so it mutes the clack without softening the feedback. You feel every keystroke, just without the noise.

What is the Gazzew Boba U4 silent tactile switch?

The Boba U4 is a silent tactile switch that Gazzew designed with Outemu. It targets people who want to feel a key press without making noise. The “U4” is short for Euphoria, the vendor product page notes.

The switch borrows the Cherry MX housing shape but swaps the usual all-nylon shell for a soft, milky “Pearl” housing made from Gazzew’s own Boba plastic blend. That blend is softer and smoother than nylon-66, so it mutes metallic spring and leaf noise on its own.

The quiet comes from the stem. Silicone dampeners sit on the stem and absorb the impact at both ends of the press, so the top-out and bottom-out clacks both go away. It ships in 62g, 65g, and 68g spring weights, with a color-matched Boba top or a clear top for RGB builds.

Two sibling switches are easy to mix up. The non-silent Boba U4T (Thock) shares the same D-bump but adds a longer, thockier stem. The earlier Outemu Silent Sky is a lighter, P-shaped bump from the same Gazzew and Outemu team.

How does the Boba U4 stay tactile while silencing the clack?

Most silent switches quiet the noise with silicone pads that also cushion the bump. That’s why they feel dead and mushy. The Boba U4’s whole pitch is that it avoids that trade.

The dampened stem handles the noise. Silicone dampeners absorb the impact at both ends of travel, and the soft housing mutes spring-ping and metallic leaf tick. What’s left, per the Switch and Click review, is a “scratchy thud” or “thunk” instead of a clack.

The bump shape keeps the feel. The Boba U4 uses a D-shaped bump with almost no pre-travel, so the bump starts at the very top of the press and runs nearly to the floor. In practice, the whole keypress feels like one long bump. That is what keeps it from going mushy.

Because there is no pre-travel before the bump, the switch feels sharper than dampened rivals even though it is silenced. The reviewer notes the Novelkeys Blueberry feels more tactile at first but mushier overall, for exactly this reason. A tactile copper leaf carries the feedback, and the round D-bump reads as stronger and fuller than the Holy Panda, Glorious Panda, T1, and Outemu Sky.

The result earns a memorable line from reviewer Randall Jue:

One real limit: actuation happens after the bump. On a heavy typing style, the actuation point can sit close to bottom-out, which is part of why some testers still get a faint membrane-like impression.

Does the Boba U4 feel better in 62g or 68g?

The stem and housing stay the same across weights. Only the push weight changes, and that changes how the bump reads.

The 62g spring is lighter, so it makes the tactile bump feel sharper and more pronounced. The 68g spring feels smoother and more planted while keeping most of the tactility. Its heavier floor also means fingers resting on the keys will not trigger an accidental press.

It helps to think in terms of peak force, the most force you need to push past the bump and actuate. A tactile switch already needs more peak force than a linear on the same spring. The heavier 68g raises that wall further. A 65g option sits between the two for buyers who want to split the difference.

Choose 62g if you chase the crispest bump, and 68g if you want a calmer, smoother press that still feels tactile.

Will the Boba U4 fit my keyboard and hot-swap sockets?

The Boba U4 is a 5-pin Outemu switch. The five pins give more stable seating on a PCB, and it drops into MX-style boards like any standard switch. Its universal base carries an RGB slot that works with all LED styles.

The compatibility list is broad. The vendor page lists it as compatible with 7305 Mill-Max sockets, Kailh and Gateron MX hot-swap sockets , and Outemu-only sockets. That Outemu-socket fit is the useful part: those sockets are known to be too tight for switches from other brands, so an Outemu board finally gets a premium tactile option that seats properly.

There is a reverse issue on a 5-pin part. On some hot-swap boards you may need to clip the two extra plastic legs down to a 3-pin footprint before the switch sits flat. The housing itself is tight enough that the switch shows no wobble and needs no switch films, though a thin film can tune the sound if you want it.

One note for RGB builds: the clear top suits per-key RGB. Because both strokes are dampened, there is no sound difference between the clear top and the color-matched Boba top. On non-silent switches, the two tops would sound different.

Boba U4 versus a typical silent linear

A silent linear trades away all feedback for a smooth, quiet glide. The Boba U4 keeps the quiet but adds a large, deliberate bump, so it aims at a completely different typist.

Against a loud tactile, the U4 keeps nearly all of the bump and peak force. It drops the top-out and bottom-out clack and most of the spring-ping and leaf tick. The cost is small: a stock switch can feel a little scratchy, and the silenced landing feels softer than a hard plastic bottom-out, which can bother anyone new to a dampened stem.

It runs well from the factory with minimal scratch, so lube is optional. A light lube removes remaining scratch and any lingering ping. Unlike many silent switches, it does not need films to feel tight.

The silicone dampeners also pull out. Removing them makes the stem sit higher, adds a little pre-travel, and gives a milky clack like a Gateron Milky Black linear. In effect, you can convert the feel back toward a non-silent switch.

The verdict: if you want to feel every keystroke but cannot make noise around colleagues or family, the Boba U4 is the silent tactile that does not go mushy to get quiet. Independent testing backs the value too: ThereminGoat scored it 85 out of 100.