One of the biggest reasons why wallets become thick is because coins pile up inside. The Tenuis 3rd generation is equipped with a unique coin divider to solve this problem. 
When you open the zipper, you'll see that the interior is divided into upper and lower sections. This divider prevents all your coins from piling up in one place, such as at the bottom, and distributes them evenly throughout the wallet. In other words, you don't have to consciously organize them; just putting them in your pockets "automatically thins out." If you have a lot of coins, you can easily distribute them by sorting them by hand or by shaking the wallet after closing the zipper.
Just pull the zipper and everything is done. This simple and rational usability is the reason why the third generation has been loved for so many years. It is still in use even now that the fourth generation has been released.
Tenuis 3rd Generation
https://solahanpu.com/products/tenuis-third