ltm ltm x [sn] Merino Poly 50/50 Sleeveless (Relaxed Neck)
Shipping
International shipping is available (EMS from Osaka, Japan). Shipping cost is calculated at checkout.
Orders usually ship within 3 business days after payment is confirmed.
No shipments on Tuesdays (store closed) or during the year-end holidays.
Returns & Exchanges
Cancellations, returns and exchanges for customer convenience are not accepted.
If an item is defective or differs from your order, contact us by phone or email within 3 days of delivery. We will exchange it, or refund if no stock is available.
A spring-through-fall base layer that lets your underarms breathe
A sleeveless base layer born from a collaboration between ltm (led by mountain YouTuber Kotaro) and [sn] (Super.Natural). Built around that moment on a spring-through-fall climb when you start sweating almost as soon as you begin — designed to be worn under a mountain shirt. Without sleeves, airflow around the underarms increases significantly, and trapped heat escapes more easily with every breeze. Pairing it with a long-sleeve shirt on top keeps concerns about sunburn, tick bites, and the clammy feel under rain gear in check, while making it easier to manage your body temperature on the move.
Why 50% merino / 50% polyester
A half-and-half blend of 50% Australian merino wool (18.5 microns) and 50% polyester. Fabric weight is 143g/m², a balance suited to spring through fall. Pure wool feels great on day hikes or moderate routes, but on multi-day treks, the previous day's sweat can linger and feel cold in the morning. Blending in quick-drying polyester helps you avoid that cold, damp feeling at the start of the day. The yarn uses compact spinning, which keeps fuzz down for a smooth feel against the skin while holding up to the durability demands of a mountain base layer.
Four-panel construction and flat-seam stitching
Built from four panels — front, left side, back, and right side — for a fit that follows the body. The seams use flat-seam stitching to minimize bulk, keeping the surface against your skin as flat as possible. This construction resists chafing and rubbing from seam allowances even over long days. The hem length is tuned to sit well under a shirt without bunching up as you move.
Relaxed neckline and armhole design
The neckline is relaxed. The 2026 update widens the opening by about 5mm more, so heat doesn't build up around the neck on a climb where you sweat easily. The armholes are kept intentionally smaller for a more composed look with less exposure. Rather than leaning purely sporty, it blends naturally when layered under a mountain shirt.
Final finishing in Bishu
Final finishing takes place in Bishu, one of the world's three great wool-producing regions. The soft-water finishing process brings out merino's smooth feel against the skin and natural sheen, adding a refined texture on top of its performance as mountain wear.
Size and fit guide
A body-following base-layer fit, designed to be worn with a long-sleeve shirt over it. Sizing extends up to XXL in addition to XL to accommodate larger frames. For height guidance and detailed measurements, check the size guide in our size selection section.
| Use | Spring-through-fall sleeveless base layer for mountain use (designed to be layered under a long-sleeve shirt) |
|---|---|
| Material | 50% merino wool (Australian, 18.5 microns), 50% polyester |
| Fabric weight | 143 g/m² |
| Spinning | Compact spinning (smooth feel and durability) |
| Construction | 4-panel (front / left side / back / right side) |
| Seams | Flat-seam construction (reduces seam contact) |
| Neckline | Relaxed neck (2026 version opens about 5mm wider) |
| Armhole | Smaller cut (for a more casual look) |
| Finishing | Final finishing in Bishu, Japan. Soft-water finishing for a smooth feel and natural sheen |
| Model | ― |
About stock
Inventory is shared between our physical store and the online store, so an item may become out of stock after you place an order. If that happens, we will contact you promptly. Thank you for your understanding.