The most common booster hose is the durable nitrile synthetic rubber-covered booster hose. This is a red, thick-walled, flexible hose used to fight small fires available in 3/4", 1" and 1 1/2" inside diameter and is designed to operate at pressures up to either 300 psi or 800 psi in the smaller sizes and up to 150 psi in the 1 ½” diameter. The 800 psi versions have a slightly harder rubber compound for greater strength and durability.