ltm Merino Relaxed Action long T

Fleece runs too hot, a T-shirt runs too cold. This long sleeve fills that gap.

The Merino Relaxed Action long T is a 2026 model from the collaboration between ltm, run by mountain YouTuber Koutaro, and [sn] (Super.Natural), known for its merino daily wear. It's built to bridge the moments when "fleece is too hot, but a T-shirt alone isn't enough" as body temperature swings during activity. Designed as a thin layer that sits just one step before your base and mid layers, it works across late-autumn-through-early-spring mountain days and everyday errands alike.

The idea of a "thin mid-layer"

In the mountains, heat builds up as you climb, then drops fast at a rest stop or in a ridgeline wind — that back-and-forth between moving and stopping is constant. This piece is designed to sit in the gap between a base layer and a fleece, as one thin layer you reach for just before adding more. At 143 g/m², with a blended construction, sweat escapes easily and the fabric recovers quickly once wet, which helps hold off the chill that follows.

It also holds up under rain gear. Even if the inside gets damp from rain or condensation, it dries back out fast, so you're less likely to carry that cold, clammy feeling once you're moving again.

Material design: a 50% merino / 50% polyester balance

Temperature and moisture regulation, plus quick drying

Merino wool regulates temperature and moisture well, but 100% wool is slow to dry once wet — a real risk on overnight trips or inside rain gear where conditions change fast, where lingering dampness can pull away body heat. This piece blends in 50% polyester, so the fabric dries quickly even after sweat or rain. The blend keeps both the sweat from activity and the chill from a rest stop from dragging on. It's merino's comfortable temperature and moisture regulation, plus polyester's quick-dry performance — a practical answer built for actual use in the mountains.

18.5-micron merino on a 143 g/m² lightweight fabric

The fiber diameter is 18.5 microns — the smaller the number, the gentler it feels against skin, with less of the itch wool can bring. Fabric weight is 143 g/m², deliberately lighter than the roughly 150 g/m² typical of wool base layers, to keep enough thickness that it doesn't show through while prioritizing quick drying and year-round usability. Despite being thin, it still carries the strength it needs, making it an easy piece to reach for when the season is in between or you're not sure how hard you'll be moving that day.

Yarn and fabric: the smoothness of compact spinning

The yarn is made with "compact spinning," a process that bundles fibers together with air and twists them in a way that wraps in the loose fuzz. This keeps pilling — a common issue with wool/polyester blends — noticeably more in check than with standard spinning. With less surface fuzz, the fabric feels smooth and light against the skin, with less of that itchy feeling.

Less fuzz also helps the color. Dye takes more evenly, so the color comes through clean and clear — whether a muted tone or a vivid one, each comes through as intended. It's a fabric built to deliver both feel and color, for wear that moves between the mountains and daily life.

Patterning and details built for movement

A wider neckline for natural ventilation and easier layering

The neckline is cut wider than the previous model (the 4seasons long T), since the neck is the first place heat builds up as your body warms. That lets heat vent naturally as you walk, and keeps the neck from feeling tight even when you layer a fleece or shell over it.

Y-joint sleeves keep the hem in place even with your arms raised

The Y-joint sleeve construction, with the sleeve seam shaped like a Y, opens up a wider range of motion at the shoulder. Reaching up on a rock scramble, rolling over in a tent, adjusting a pack's shoulder strap — the hem stays put rather than riding up, so your lower back stays covered.

A slightly longer hem and a longer rib cuff

Modeled on 1950s vintage sweatshirts, the body length runs a touch longer, covering the hips well so your back and midriff stay covered even when you bend over. The hem rib is also cut longer, holding its line even as you move.

Shoulder seam shifted toward the back

A shoulder seam sitting right where a pack's shoulder harness rests can turn into real discomfort over a long day of walking. Shifting the seam toward the back moves it out of that contact point.

No thumbholes, by choice — sleeves run slightly long instead

To keep the look from leaning too far into "mountain gear," thumbholes were deliberately left out. The sleeves run slightly long instead, so pulling your hands in still covers the backs of your hands. The result reads just as natural in the mountains as it does around town, while still guarding your hands from the cold when you need it.

A flat-seam construction that's gentle on skin

Flat-seam construction keeps the seams from sitting proud, so there's little rubbing or irritation against bare skin. It's the same construction used in competitive swimwear and top-level athletic gear, and it keeps things comfortable over long hours of wear.

A subtle collaboration logo

The ltm × [sn] collaboration logo sits quietly at the bottom left hem — a small detail, not an attention-grabber, for the mountains or daily life alike.

Color character and how to choose

Available in Soft Natural, Pale Purple, Yamabuki Gold, and Midnight Navy. The clarity that comes from compact-spun yarn carries straight through into how each color reads on the fabric.

Soft Natural

An undyed, natural tone. It runs a touch sheer by nature of the color — a trade-off the brand knowingly accepted at the design stage. It also brightens up the face nicely. If you're wearing it alone, layering a crew-neck dry layer underneath (Millet's Drynamic Through II, for example) helps cut down on the sheerness. Worn as a thin mid-layer over something else, you can choose it without worrying about a dry layer at all.

Pale Purple and Yamabuki Gold

Both mellow with wear over time — Pale Purple deepening into a more subdued shade, Yamabuki Gold settling into a warmer, more muted tone. You get the vivid look when it's new and a worn-in, mellowed character later on — two different moods from one piece.

Weight and packability

Weight is about 180g (the same across all sizes). That's light for a thin mid-layer, and it tucks easily into any gap in a pack. On days when the temperature is hard to read, that light weight makes it easy to keep adjusting by putting it on or taking it off.

How to layer it

• Worn alone: on high-output days with little wind. The wider neckline lets it vent naturally.
• Over a base layer: add it over a T-shirt or sleeveless top to manage the morning and evening chill.
• Under rain gear: even on wet days prone to condensation and clamminess, the blend resists holding onto dampness.
• As an extra layer at rest: a quick "one more layer" against the chill of stopping.
• Deep winter: sandwich it between a base layer and a fleece to fine-tune moisture release and warmth — or wear two for extra warmth.

Who it's for

• Anyone caught between seasons or itineraries where fleece runs too hot but a single T-shirt feels thin
• Anyone who wants to manage sweat-chill while still caring about how it feels against skin
• Anyone who wants one piece that looks right from the mountains to daily life

Spec

Size

Measurements taken flat. Body length is measured from the back neck center to the hem. Actual garments may vary slightly from the listed measurements.