Japanese mat  - made of twisted polyester fiber and a special waterproof binder.
The mats are stiff, easy to use, easy to clean and  designed for long-lasting work . It works perfectly as a sprinkled or completely submerged material.
Japanese mat is a filtration medium recommended by professionals all over the world. It is worth paying attention to the durability of Japanese mats -  they are incomparably more durable than coconut mats.  

The mat is used in filters for ponds, and large aquarium filters.
It provides the right filtration environment, gives a huge surface for bacterial deposition, and at the same time allows proper, free flow of water through the filter.