Bitcoin Sports Shirt - Proof of Work

Bitcoin writes its transactions into blocks. For a block to become valid, miners have to compute until they find a number that meets a set condition. That only works by trying, billions of times over, with real machines and real electricity. There is no shortcut.

The decisive point is the asymmetry: the work is expensive to do and can be checked by everyone in the network in fractions of a second. Anyone who wanted to change an old block would have to do the work for that block and every block after it all over again, faster than the rest of the network, which keeps computing. That is exactly where the security of Bitcoin comes from: not from a promise, but from energy spent.

In training it is the same principle. The repetitions you have done, nobody can take off your hands and nobody can fake. In the end the work counts, not the announcement.

The Bitcoin Sports Shirt is made for sessions that get you warm: strength training at the gym, intervals, functional training, cycling, warm days outdoors. The polyester dries quickly and does not stick to your back when the sweat comes. Under a jacket it works as a first layer, because it passes moisture to the outside.

What it is not made for: long runs in the heat, where every gram and the airflow count. That is what the Bitcoin Running Shirt is for. And if you are looking for a shirt for everyday wear that feels softer and does not look like sportswear, go for the Bitcoin T-Shirts.

Regular fit. Our model is 1.90m tall and wears size XL

All measurements in cm. Slight production-related deviations of +/- 2.0 cm are possible.

• Machine wash cold (30 °C), wash with similar colors
• Tumble dry at low temperature
• Iron at low temperatures
• Only use chlorine-free bleach
• Do not dry clean
• Do not use fabric softener
• Wash before wearing

Fabric softener lays a fine film on the fibers and seals them; after that the performance fabric no longer pushes moisture to the outside but holds on to it. So: wash without fabric softener.

100% polyester

• Shipping to Germany, Switzerland and 17 other EU countries for €4.99
• Free shipping from €75 order value (the amount after any discount applies)
• 14-day right of withdrawal from receipt of the goods
• Return shipping is paid by the buyer
• The statutory warranty applies under the rules of your country

You will find the full terms under Shipping policy and Refund policy.

How do I find the right size?

Above you will find our fit and wearing note for this item. If you are between two sizes, take the larger one — in most cases that is the better choice. If you are unsure, just message us and we will help.

Is the Bitcoin21 logo embroidered or printed?

On this item the logo is printed, not embroidered. The print lies flat on the material and does not add texture.

How do I wash this correctly?

Follow the care instructions above. Technical fabric does not like high temperatures or fabric softener — both damage the fibres. Washing inside out protects the finish.

What if the size does not fit?

You have a 14-day right of withdrawal from receipt. Send the item back and order the right size — return shipping is paid by the buyer. A look at the measurements above saves you the trip in most cases.

Can I pay with Bitcoin?

Yes. Alongside the usual payment methods you can pay us directly in Bitcoin. For a shop that embroiders Bitcoin onto clothing, anything else would ring hollow — we back Bitcoin as a means of payment, not just as a design.