Simcro rigid back-pack drench containers are moulded in high-density polyethylene to withstand heavy duty use. They can stand on their base to fill, and are then used in an inverted position for gravity feed. A duckbill valve in the red outlet cap allows air inlet. This cap has a dual spigot to suit 6.4mm or 9.5mm delivey tubes. Black storage cap and back-pack straps are supplied (in the pack wall cavity).