The food in this type of feeder is only available when poultry stand on the step plate. The feeder shutter then opens and the feed is available. This prevents access and contamination by birds and vermin. This is all activated by the weight of the bird - which can be set from 250gm to 5kg. The feed chamber has space-dividers to keep birds from competing with each other. Also an anti-spill lip to prevent fall-out of feed. The feeder is completely weatherproof. All zinc-plated with glass-nylon lid and step plate. Dimensions: 5kg = 26 x 28 x 40cm high; 8kg = 26 x 28 x 45cm high; 12kg = 33 x 23 x 50cm high; 20kg = 33 x 26 x 66cm high. Needs minor assembly on receipt. Instructions included. From Europe.