13. The cylindrical shape thing is called a ferrite bead.
They exist at the ends of chargers in laptops and computers. They are used in suppressing high-frequency noises and isolates the laptop from electromagnetic noise.
14. Do you know why there is a loop at the back of a shirt?
Some say it used for attaching a tie at the back, and also to hang on a hook properly.
15. The dots that come in bottles are not Brailles.
Those are codes use in the production process to mark the authenticity of the product.
16. Fancy an elbow patch but don’t know it’s purpose?
During the war days, Soldiers had to crawl around a lot on their elbows and that area of the cloth would thin up and tear. That is the reason why they added extra layers of patches.