Prozapยฎ StandGuardยฎ Pour-on is the ideal horn fly and lice control solution that is powerful, low-dose, and easy to use. No dilution is necessary, and Prozap StandGuard is available in 16 fl oz (473 mL) and 30 fl oz (900 mL) bottles with an easy squeeze-and-pour design ideal for smaller treatment groups. Prozap StandGuard is also available in 4.5 L size, which is more convenient for large operations.