This Hydro mat is perfect for use in many styles of vivariums, and can be easily cut down to fit whatever project you're working on. This is designed to be used above the level of Hydro Rocks, to ensure the soil doesn't seap through and clog in the drainage.
By having your water reservoir underneath, this allows the water to be drawn upwards and keep the top layer of substrate, be that soil or sand, moist and fresh. This means you can keep plants easily, providing them with fresh water and good drainage, so they can thrive.
This is also an important part of keeping custodians, such as Springtails or Woodlice, meaning them have fresh substrate to live in, so they can easily keep the environment clean and healthy.