Stop wasting your organics! Turn them into the best garden bio-organic you will ever have.The thermal insulation in the Aerobin stabilizes temperature all year round to create the perfect environment for “hot composting”, a process which not only speeds up the time needed to break down organic matter but also kill any dangerous pathogens, weeds and seeds that could could potentially be a risk to your garden. With a patented design that embodies innovation and technology, the Aerobin can accommodate a variety of organic materials such as food scraps (including onion and citrus), tea leaves, lawn clippings, leaves, twigs and even newspaper. Tested and endorsed by Swinburne University of Technology, Environment and Biotechnology Centre in Australia 200L vs 400LBoth models operate the same way and have the same features.The 200L is generally a great size for a couple. The 400L is a much better option for Families with a higher output of organic material.