Featured Switch: HMX Rain — A Rail Bottom-Out Linear Built Around Texture
Introduction
This week's featured switch is the HMX Rain (Rail Bottom-Out), designed by Youth Studio. It has recently been one of the most viewed switches on KeyLab DB.
Where most linear switches compete on smoothness, the Rain is built to feel evenly scratchy from the top of the stroke to the bottom, and pairs that with a rail bottom-out (RBO) structure. It is a linear with an unusual personality.
The short answer
| If you... | Fit |
|---|---|
| Want some feedback from a linear, or enjoy texture | Good fit. Tuned for an even, scratchy feel through the stroke |
| Want a light switch for long typing sessions | Good fit. Around 42g actuation |
| Like the Azalea and want to try a different bottom-out | Good fit. It is the Azalea's rail bottom-out version |
| Want a linear that feels completely smooth | Not a fit. The texture is intentional |
Specs
Based on KeyLab DB data and the retailer's (UniKeys) product page, as of September 25, 2026. Prices change.
| Item | Details |
|---|---|
| Type | Linear (rail bottom-out) |
| Pins | 5 |
| Actuation force | 42g (KeyLab DB) |
| Bottom-out force | 50g (KeyLab DB) |
| Pre-travel | 2.0mm ± 0.2mm |
| Total travel | 4.0mm ± 0.2mm |
| Stem | POM blend |
| Housing (top/bottom) | PA66 with fiberglass |
| Spring | 20mm single-stage |
| Lubrication | Factory lubed |
| Designer | Youth Studio |
| Reference price | 3.8 USD per 10 (UniKeys) |
Highlights
Even texture through the whole stroke
According to the retailer, the top housing has matte guide rails and updated stem-mold parts so that the same sandy feel continues from the top to the bottom. The housing is fiberglass-filled PA66 for stability, and the stem is a POM blend chosen for its textured surface. The goal is a switch that is scratchy without any sudden catch partway down.
Factory lube that keeps the texture
The lubrication works the opposite way from most linears. The spring and stem get only a thin dry film to keep the texture, while the leaf and the spring-contact area of the bottom housing are evenly lubricated to control metallic noise (spring ping). Keep the feel, remove the noise.
Rail bottom-out (RBO)
When fully pressed, the rails on both sides of the stem hit the housing instead of the center pole. The retailer describes the sound as high-pitched, clacky, and crisp. One YouTube review is titled "They FINALLY Made A Good Rail Bottom-Out Switch," and the Rain is among the better-received RBO switches.
Compared with the Azalea and Snow Crash
The Rain is the rail bottom-out version of HMX's Azalea. HMX also makes another RBO switch, the Snow Crash (a collaboration with Keebscape.co). Here they are side by side using KeyLab DB data.
| Switch | Actuation | Bottom-out | Total travel | Bottom-out structure |
|---|---|---|---|---|
| HMX Rain | 42g | 50g | 4.0mm | Rail bottom-out |
| HMX Azalea | 42g | 50g | 3.8mm | Standard |
| HMX Snow Crash | 50g | 58g | 4.0mm | Rail bottom-out |
Against the Azalea, with nearly identical forces, the main difference is how it bottoms out. If you want to try RBO at a heavier weight, the Snow Crash is the one to look at.
Conclusion
The HMX Rain steps away from the idea that a linear should be as smooth as possible. It is a switch for enjoying texture and a solid bottom-out. At around 42g it is easy on the fingers, and at 3.8 USD for ten it is cheap to try, so swapping it into a few keys on your current board is a good way to compare.
Explore more
Sources
FAQ
- What is rail bottom-out (RBO)?
- When the key is fully pressed, the rails on both sides of the stem hit the housing and stop the stroke, instead of the center pole. Changing where it bottoms out changes the bottom-out feel and sound, even with the same materials.
- How is it different from the HMX Azalea?
- The retailer describes the Rain as the rail bottom-out version of the Azalea. In KeyLab DB, both have the same actuation and bottom-out force (42g / 50g), with a total travel of 4.0mm for the Rain and 3.8mm for the Azalea.
- Will it suit me if I like smooth linears?
- The Rain is designed to feel scratchy from top to bottom. If you want a linear with no texture at all, another switch is likely to be a better fit.
