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- Product Story
- How to Use
- Form and Function
- Insulated, Just the Front
- Thermal Comparison
- Excellent Air-permeability
- Even Warm When Wet
- Ultralight and Packable
- Polartec Alpha Direct
- Shadow Rip: Lightweight, Strong, Durable
- Care Instructions
Ultralight, Minimal Active Insulation
Feeling a little chilly? Wear this vest over your base layer. This is an ultralight and simple vest-style active insulation, suitable when you are on the move.
The front part uses thick Polartec Alpha Direct (136g/m2), which is thermal and air-permeable. It prevents overheating and offers great comfort when in action. If it’s chilly when resting, wear a shell over it to keep your core warm. The vest also boosts the warmth around the abdomen and chest of the body if you sleep wearing it.
The back of the vest is not insulated and is made of one piece of highly breathable, ultralight Shadow Rip* used for the UL Shirt, prioritizing the lightweight and compactness. This is because your back is usually insulated by your backpack when you are on the move, or by the sleeping pad when you are asleep.
It is also recommended to wear it with a highly air-permeable All-weather series jacket!
*The fabric has been revised from Pertex Quantum Air to Teijin Shadow Rip since 2022.
Made in Gifu, Japan
Front: Polartec Alpha Direct (100% Polyester) 136g/㎡
Back: Shadow Rip (100% Polyester) 56g/m²
69g (Size S)
77g (Size M)
84g (Size L)
93g (Size XL)
UNISEX | S / M / L / XL
Akira Natsume, Yamatomichi Founder
Through the development of the Alpha Anorak and the Light Alpha Vest/Jacket, I realized the usefulness of Polartec Alpha Direct as an insulator and was curious to make a lighter and more minimalist product. In the Alpha Haramaki tests, I wrapped the Alpha Direct fabric around my stomach, and it felt great and was warm enough.
How can I create hiking gear that is more simple, versatile, and reasonable in terms of price than a jacket? My answer is our new Alpha Vest.
From the beginning of the development in 2019, we decided to make a vest-style product. The first prototype vest was entirely made of, including the back, Alpha Direct, but we settled on using it for the front part only. The reasons for this are as follows.
- Enhanced Durability The Polartec Alpha Direct was originally designed to be used in combination with outer fabric, and fur came off after repeated friction. Thus, I decided to use the air-permeable and ultralight fabric for the back and shoulders where the backpack constantly comes in contact. The fabric has been changed to Shadow Rip, which is the same material used for the UL Shirt since 2020.
- Lightness and Packability The back uses lightweight Shadow Rip, making it so small and compact that it fits your pocket.
When I used the Vest in the mountains, I found it useful and comfortable because it was highly air-permeable, preventing heat from building up during activities. If you wear a shell over it, you can block the ventilation and keep your core warm. To be honest, it is not that warm when you stop to rest, and your arms and back may feel cold. But if you’re in the summer mountains, where you don’t need a down jacket, this Vest should be just warm enough. If you are a fastpacker, you can choose to bring only this vest for warm clothes, and use a slightly warmer sleeping bag instead.
I feel that the UL All-weather series transmits body heat more smoothly to my sleeping bag than other conventional outerwear, so if the season is right and if you are a minimalist hiker, you may be able to sleep in with the UL All-weather and Alpha Vest.
The Alpha Vest is a novel hiking gear that is minimal, simple, and versatile.
How to Use
Use When You are on the Move
Use the Vest as warm clothing for chilly weather when you are on the move. The front insulation effectively keeps the chest and abdomen warm, while the outstanding breathability releases heat, keeping you comfortable while in action.
Keeps You Warm When Resting
When resting, wear a shell or shirt over the top. The front Polartec Alpha Direct protects your abdomen and other core parts of the body from getting cold.
Minimalist Warm Clothing for Bedtime
In the summer mountains, the ultralight Alpha Vest works as a backup, warm sleeping clothes instead of an inner down jacket.
Form and Function
Insulated, Just the Front
The front is made of the Polartec Alpha Direct, which has excellent insulation and breathability, while the back and shoulders are made of ultra-thin and highly breathable Shadow Rip; only the front part is insulated. It is because the back and shoulders tend to get hot while on the move when you carry the backpack, and when you are asleep, your back is usually contacted with the sleeping pad and you rarely feel the cold.
Although it is not as warm as 1000 fill power down, the slightly thick Polartec Alpha Direct (136g/m2) used in the Alpha Vest is one of the best insulators available. The Alpha Vest can be used not only in action but also when resting, always keeping you warm.
The below chart compares the 1000 fill power down and other insulators used in thermal clothes on the market.
- 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 fabric, achieving even higher breathability. It is warm but not too warm because heat and moisture can properly escape, always keeping you comfortable.
The below chart compares the breathability of middle layer products*.
*Measured by JIS 1096A (Frazier method), in Yamatomichi in-house test.
Dries quickly even when wet with sweat.
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.
Even Warm When Wet
The Polartec Alpha Direct, like other synthetic insulators, rarely retains water and its loft is kept bouncy even when wet; It is warm even when you sweat or under the light rain.
Ultralight and Packable
It is lighter than a normal T-shirt, about the size of a 350ml can when folded.
Polartec Alpha Direct
- Excellent air-permeability and thermal performance
- Outstanding lightness and packability
- Polygiene treatment for semi-permanent antibacterial and odor-control
Conventional natural down and synthetic insulators tend to contain body moisture within the clothes and as a result, can be quite stuffy. Polartec Alpha Direct, on the other hand, is so air-permeable that it can be worn even during a high level of physical activity.
Polartec Alpha Direct (100% Polyester) 136g/㎡
Bursting strength measured by JIS L1096A (In-house test)
Heat retention measured by JIS L1096A (In-house test)
Heat retention measured by ASTM F1868 (Catalog spec)
Min: 0.80CLO, Max: 1.60CLO
Shadow Rip: Lightweight, Strong, Durable
The mountain environment can be harsh; the weather is often unstable, temperature changes drastically, the wind is strong and the sunlight is intense. In these situations, it is necessary for the outdoor shirt to achieve both a high level of breathability and windproof performance at the same time. Our newly-adopted Teijin’s Shadow Rip fabric is breathable yet windproof while being light and strong.
Usually, thin and light fabrics have a ripstop structure, in which thick yarns are interwoven in a grid pattern in order to enhance tear resistance. This structure, however, often creates an unsmooth surface, causing the pilling due to weak wear resistance.
Shadow Rip is woven with fine, highly strong yarn to achieve a smooth appearance, and offers excellent resistance to snagging and abrasion while being light and strong. It is also wrinkle-proof and pilling-proof, featuring a soft texture.
Shadow Rip™ (100% Polyester) 56g/m2
Tear strength measured by JIS L1096D (In-house test)
Vertical: 1.4kg, Horizontal: 1.5kg
Tensile strength measured by JIS L1096A (In-house test)
Vertical:47.1kg, Horizontal: 42.8kg
Breathability measured by JIS 1096 A (In-house test)
推奨サイズ / Recommended Size
|体重 / Weight
|胸囲 / Chest
製品サイズ / Product Size
|着丈 / Length||69||72||74||76|
|肩巾 / Shoulder Width||36||38||41||44|
|身巾 / Body Width||48.5||51||55||60|
|裾巾 / Hem Width||47.5||50||54||59|
- Use neutral detergent. Machine wash, gentle or delicate at 30°C or lower.
- Wash separately or use a laundry net.
- When the back fabric of this item is wet from perspiration and in contact with white or light-colored wool or silk clothes for a long period of time, the components in perspiration may cause the color transfer.
- Wash to remove the perspiration after use.
- Avoid bleach or fabric softener.
- Line-dry in the shade.
- Tumble dry, low at 60℃ or lower.
- Do not iron. Do not dry clean.
- If necessary, wash to remove the fuzz from the fabric before first use.
- We only accept payment by credit card. We currently do not accept payment via bank transfer from overseas accounts.
- We accept the following Credit Cards: Visa, Master, American Express, and JCB.
- To download your receipt, please click the link included in the Dispatch Notice, which we will send by email as soon as the items are dispatched.
We will ship by DHL for overseas customers (excluding China, Hong Kong, Taiwan, Korea and Russia). For customers in China, Hong Kong, Taiwan, Korea and Russia, we will ship by EMS only. Shipping costs vary depending on your country and region.
- Overseas customers who need to change the size of their order, should note that the time needed for shipping will vary greatly depending on your country of residence.
- We only accept exchanges when the item is unused (except for fitting).
- If you wish to exchange the size of the item, please contact us within seven days of receiving your order.
- Exchanges can only be made for the same color in a different size.
- If the size you wish is out of stock, we will suggest a different color.
- If the product is out of stock, we may simply have to ship the item back to you.
- All shipping costs to be carried by the customer.
- We will only send the exchanged item to you, upon receipt of return shipping cost via PayPal.
- Please be aware that some countries charge customs duties depending on the price of the item.
- We are unable to answer any questions on local customs. Please contact your local customs bureau.
We accept repairs for all of our Yamatomichi products. For inquiries on repair services including patching the holes, repairing with extra components, or fixing the items damaged over time, please feel free to contact us from the “Repair” section of the SUPPORT page.