SUN-MAR's NEW Garden Composters incorporate a patented double drum Autoflow design. With Autoflow, material goes in the top and compost exits out the end as the drum rotates. As the drum rotates, compost moves along the outer drum and then back through the inner drum before dropping from the output port. compost discharges automatically - no waiting for compost batches to finish - pest resistant - easy loading and turning of the composter. 195 Liter Drum. Assembly is easy! Because so few pieces are used the SUN-MAR 200 can be assembled in 2 minutes, and the 400 in 5 minutes.