Harkers 4-in-1 Soluble is an effective treatment to be given in the drinking water, for canker, coccidiosis, worms and external parasites. It is for the treatment and control of coccidiosis, treatment of hairworm and roundworm infections, and therapeutic and routine treatment of canker. One bottle treats 50 birds. This is a flock treatment for canker, coccidiosis, worms and external parasites (lice and mites) in racing pigeons which can be simply added to the drinking water.