The Alpha Vest, our most minimalist insulation layer, now features a kangaroo pocket made from Shadow Rip. This fabric offers just the right balance of breathability and wind resistance, shielding your core from cold gusts without causing overheating.

The front of the vest uses Polartec Alpha Direct (136g/㎡) to provide warmth and airflow, preventing heat buildup during movement. The back and shoulders are made entirely from lightweight, breathable Shadow Rip to help minimize sweat when wearing a pack.

A minimalist layer for hikers who won’t stop to put on a shell—essential protection in motion.

Key Features

• Polartec Alpha Direct (136g/㎡) for lightweight, breathable insulation
• Shadow Rip fabric on back and pockets for light wind resistance
• Keeps core warm, reducing need for a shell
• Stays warm when wet and dries quickly
• Lightweight and highly packable
• Great as an active layer or minimalist insulation piece

With Polartec Alpha Direct insulation placed only on the front, this vest keeps your core warm while allowing excess heat and moisture to escape. The result is exceptional breathability that helps maintain a comfortable body temperature during high-output activities.

The kangaroo pocket, made from wind-resistant Shadow Rip, adds extra protection at your stomach—shielding you from wind without sacrificing airflow. Thanks to this added defense, you’ll find yourself reaching for your shell less often than with the standard Alpha Vest.

Layer a shell or shirt over the Alpha Vest for added warmth. This is especially helpful when you stop to rest.

When a down jacket feels like overkill, the Alpha Vest is a great alternative for staying warm at night—without the bulk.

The front of the vest features Polartec Alpha Direct, offering an ideal balance of warmth and breathability. In contrast, the back and shoulders use ultra-thin, highly breathable Shadow Rip—with no insulation at all.

Why the difference? When you’re on the move with a pack, your back and shoulders heat up fast. And when you’re sleeping, that same area is pressed against a pad, compressing any insulation and rendering it ineffective. So instead of adding bulk where it won’t help, we focused warmth where it matters most: the front.

When your core gets cold, everything else starts to go downhill. In the worst-case scenario, losing warmth can mean the end of your hike.

That’s why the Alpha Vest Kangaroo includes a wind-resistant Shadow Rip kangaroo pocket—placed exactly where it matters most. It shields your core from biting wind, and you can slip in a tenugui or map for a little extra insulation. Smart. Simple. Effective.

It’s no match for 1000 fill-power down—but the 136g/㎡ Polartec Alpha Direct used in the Alpha Vest Kangaroo is among the warmest active insulation fabrics available. Designed to excel during movement, it also provides enough warmth to serve as a reliable insulation layer during rest stops.

The chart below compares 1000 fill-power down with various insulation materials commonly used in thermal garments.

• Heat retention is measured by JIS L1096A, in Yamatomichi in-house test. The heat insulation property is measured from the amount of energy consumed by the heat-generating element to maintain its temperature. The maximum value is 100%.
• The values of Polartec and Primaloft fabrics are the manufacturers’ catalog specs. Other fabrics’ values are measured by Yamatomichi. 1000 fill power down includes its 7 denier nylon outer and lining.

Highly air-permeable Polartec Alpha Direct is used on the outer surface of the vest, further enhancing overall breathability. It provides warmth without overheating, as excess heat and moisture can escape efficiently—keeping you dry, comfortable, and balanced during activity.

The chart below compares the breathability of various midlayer fabrics.

*Measured by JIS 1096A (Frazier method), in Yamatomichi in-house test.

The below chart compares the fast-drying performance of middle layer products. It is shown that Alpha Direct is not as fast-dry as the extremely fast-drying Shadow Rip (UL Shirt), but the moisture content after spin-dry is much lower than that of wool and other fabrics, and even when wet, it dries quickly if lightly wrung out or worn for some time.

*Tested by Yamatomichi. Compared the difference of the water content after completely wet and 15 minutes of spin-dry. The larger the value, the higher the moisture content, meaning slower drying.

Like other synthetic insulations, Polartec Alpha Direct absorbs very little moisture and maintains its loft even when wet. That means it continues to provide warmth when you sweat or get caught in light rain.

The mountains can be harsh, with unstable weather, sharp temperature swings, strong winds, and intense sunlight. In these conditions, both breathability and wind resistance are essential. Our newly adopted Teijin Shadow Rip fabric delivers that balance while remaining lightweight and durable.

Thin, lightweight fabrics often use a ripstop structure, with thicker yarns woven into a grid to improve tear resistance. However, this can also create a rougher surface that is more prone to pilling through friction.

Shadow Rip is made with fine, high-strength yarns that create a smooth surface with excellent resistance to friction. The result is a fabric that is lightweight, durable, soft to the touch, and resistant to wrinkling.

While the Alpha Vest is lightweight and warm, its structure—where lofted fibers are attached to a mesh fabric—can lead to some fiber shedding over time with wear or washing.

• Use a neutral detergent. Machine wash on a gentle or delicate cycle at 30°C or below.
• Wash separately or use a laundry net.
• If the back fabric becomes wet with sweat and remains in contact with white or light-colored wool or silk garments for an extended period, color transfer may occur.
• Wash after use to remove sweat.
• Avoid bleach and fabric softener.
• Do not iron or dry clean.
• If necessary, wash before first use to remove any loose fuzz from the fabric.