Brush or wildland fire engines are typically smaller than Type 1 or structural fire engines and are primarily used for vegetation fires or wildland fires. They also respond to emergencies in rural areas where traditional engines cannot respond. Most wildland engines feature four-wheel drive capability and can thus climb hills and make it through rough terrain. One of the features that makes these engines ideal for vegetation fires is that they can pump water while driving, whereas most, but not all traditional engines must be put into park to flow water, it depends on the specifications to which the Fire Department wants the vehicle to be built. A Type 5 Brush rig is often used for an initial attack, and is most often built into a medium sized pickup truck chassis.