Plastic Compost Bin Expansion Add OnTekplas Plastic Compost Bin Expansion Add On Increase Your Composting Capacity Need more space for your compost? The Tekplas Plastic Compost Bin Expansion Add On is the perfect solution. Designed to double the capacity of your 500 Litre compost bin to a full 1000 Litre, this expansion unit seamlessly attaches to either side of your existing bin. Made from high quality uPVC, its easy to assemble and will help you manage your composting more