As featured in
Built for Men. Craved by Women
Thousands of customers have shared their experience
James H. — Age 45
Ever since I put on weight, I avoided every family photo. Last weekend, I stood front and centre for the first time in four years. My sister even said I looked like I'd got back in shape.
Oliver T. — Age 33
It's not just a compression shirt. After wearing it every day for three months, my posture completely changed. I even lost weight without changing anything else. My colleagues started asking if I'd joined the gym. It's been a genuine physical transformation.
Daniel B. — Age 31
For years, I was constantly sucking my stomach in during meetings without even realising it. It was exhausting. Since wearing Underfit, I don't even think about it anymore. My shirts fit properly, and I've got my confidence back.
Matthew C. — Age 38
Honestly, I didn't believe the hype. I've always had a stomach I tried to hide under oversized T-shirts. The first time I put it on, my wife asked if I'd lost weight. I hadn't changed a thing
Ryan M. — Age 39
I wasn't expecting much. But after a month, the way I saw myself in the mirror completely changed. I'm not fighting my reflection anymore. It might sound silly, but it's the first time in years I've genuinely felt comfortable in my own body.
Ben W. — Age 36
I bought it hoping it'd make me look a bit slimmer. I wasn't expecting much more. A few weeks later, people at work started saying I looked fitter. The funny thing is, I hadn't changed my routine at all.
Feel confident again — finally feel comfortable in any T-shirt or shirt.
A sharper silhouette in seconds — helps define your chest and smooth your stomach.
Better posture, naturally — stand taller and look more confident all day.
Completely invisible — hidden under your clothes, visible in your confidence.
Size Guide
Measure around the fullest part of your chest and your natural waist. For a stronger shaping effect, choose your usual size. For a lighter everyday fit, size up.
| Size | Chest | Waist |
|---|---|---|
| XS | 34–36" 86–91 cm | 28–30" 71–76 cm |
| S | 36–38" 91–96 cm | 30–32" 76–81 cm |
| M | 38–40" 96–101 cm | 32–34" 81–86 cm |
| L | 40–42" 101–106 cm | 34–36" 86–91 cm |
| XL | 42–44" 106–111 cm | 36–38" 91–96 cm |
| XXL | 44–46" 111–116 cm | 38–40" 96–101 cm |
| 3XL | 46–48" 116–121 cm | 40–42" 101–106 cm |
| 4XL | 48–50" 121–127 cm | 42–44" 106–111 cm |
| 5XL | 50–52" 127–132 cm | 44–46" 111–116 cm |
Free delivery on all orders
Estimated within 5–7 days
Secure payment
via SSL and 3D Secure
Hassle-free returns
30-day trial, no strings attached
UK-based customer service
Available seven days a week
Why CoreArmour™
All-day compression comfort
Durable high-grade material
Undetectable beneath any shirt
Doubles as a sharp athletic top
Lightweight moisture-wicking fabric
Frequently Asked Questions
Who is CoreArmour™ designed for?
CoreArmour™ is built for men looking to slim down their appearance, regain body confidence, straighten their posture, feel more energized throughout the day, and look leaner under any outfit.
How does the CoreArmour™ tank actually work?
CoreArmour™ uses advanced Ionic Compression fabric engineered to activate your body's natural response. Its micro-weave fibers promote healthy blood flow and help you maintain an upright, alert posture from morning to night. With consistent wear, it delivers a visibly streamlined torso, better spinal alignment, and an overall boost in how you look and feel.
How quickly will I notice results?
Every body is different, but the majority of customers report a visible transformation within the first 30 days. For maximum impact, wear your CoreArmour™ daily and complement it with balanced nutrition and regular movement.
What happens if my size doesn't fit?
Not a problem at all. Simply contact us at contact@core-armour.com and our team will arrange an exchange right away.
How long does shipping take?
All orders typically arrive within 5 to 8 business days anywhere in the world. The majority of packages land well before the 8-day window, but we quote the longer timeframe to stay on the safe side.
Can I throw my CoreArmour™ in the washing machine?
Absolutely — just use a cold gentle cycle to preserve the compression integrity and extend the lifespan of the fabric.
What is the CoreArmour™ made of?
80% nylon, 20% spandex.
Rated 4.7/5 from 1,832 reviews
Absolutely love it. The fit is perfect, it's incredibly comfortable, and it gives me a much more defined shape under my clothes. I've worn it every day since it arrived.
VERIFIED PURCHASE
Really impressed with the quality. It fits comfortably without feeling too tight, and it makes a noticeable difference to my shape. My shirts fit much better now, and I've felt much more confident wearing it. Definitely worth it.
VERIFIED PURCHASE
Good material, fit just right. Comfort all Day.
VERIFIED PURCHASE
I just feel more confident wear the. For work the gym and going out
VERIFIED PURCHASE
It's very comfortable and breathes very well in the heat ,it pulls some stuff in but not that much.It is a good shirt.
VERIFIED PURCHASE
Great look, great fit except in the armpit area. Other wise love the shit style and fit I will definitely buy more
VERIFIED PURCHASE
It really does seem to work, so I'm hoping after another 3 weeks, the results will be even better. I felt the difference almost immediately.
VERIFIED PURCHASE
Before purchasing this product, I was skeptical whether to buy it or not. After watching the advertisement every day, I finally decided to give it a try, even if I might lose the money. Yesterday I received the product, and I was really surprised by how comfortable it is and how much confidence it gives you while wearing it. Now I am very happy and planning to buy more. Only one suggestion — if this product comes in a V-shape collar instead of a round collar, it would be even more beneficial and easier to hide under shirts or T-shirts.
VERIFIED PURCHASE