The rubber Duck-bill check valve is all rubber reinforced. It consists in an elastomer sleeve flattened in one end. The Duckbill valve can only be opened when the forward flow lifts the sealing flattened side of the sleeve that, otherwise its natural position is to be closed.

The rubber check valve requires no external power sources and because there is not mechanism it doesn't require maintenance, therefore it can be more competitive than other valves used for the same function such as gate valves.

Some elastomers can hand corrosive or abrasive fluids such as raw sewage, sludge or slurries. The operating temperature of the valve is limited by the elastomer temperature capacity.