The product is of poor quality; the water supply valve constantly leaks water, the spout for drinking water continues to drip even when you close it, and the water has a terrible taste after a few minutes, let alone the hours it will take. I didn't expect something that could compare to more expensive options with the money I spent, but at least the basics, which it doesn't do, is the truth. I replaced it, and the new one came with the same problem, so it must be the design

10 euros that cost me 1500 euros.. I used it only for one day, I came back home, placed it on a chair with 1 liter of water inside and left for the weekend. It burst on its own at the point you see and all the water spilled on the laminate floor.. The planks swelled on a floor that was installed just a few months ago.. The store where I bought it simply replaced the product for me. 3 weeks later and while I have it on my back with about 2 liters of water inside, it just started leaking on my back.. It opened again at the same point where the previous one opened at the bottom of the seam. I won't take it back for replacement.. They say you get what you pay for, but a plastic bottle from jumbo for 1 euro would last longer than 3 weeks of use..

On the positive side, it is very compact, the tube is comfortable and not too short, and it has a pocket for small items like keys and phone between the back and the bladder.
Now, on the negative side, the smell does not go away from the tube, so it smells like plastic (I did one wash with baking soda and vinegar), the bladder has leaked, so maybe a new tube is needed if the issue persists with further washes. Also, the mouthpiece on the bladder is not rotatable, so you have to spend more centimeters of tube inside the bag to reach it, but due to the length of the tube (it is quite long), it doesn't seem to be a problem. There is no hook on the mouthpiece (like camelbak type) to hang it on the handle, so you need a patent there, but you get what you pay for.

It easily fits in a military-style bag (similar to pentagon).
Overall, it seems to be of good quality (for 8 euros), so if you want it for running, cycling, kayaking, or just to have plenty of water with you and want to see if this style of water bottle suits you, I recommend it. I will come back later to write about the tube once I have more experience.