Kairos-green is a WPC (Wood Plastic composite) which make it highly resistant to rot and corrosion, thus it does not splinter like wood. It is resistant to water and termites as well. Varnishing is also not necessary as they are manufactured in a variety of colours.
The bad is..it is not as sturdy as wood, but it is installed right with more joints at the bottom for support, that can be mitigated. It is more susceptible to temperature changes, thus the need to have a 10-15mm gap between concrete walls and the WPC planks.