FF-2 Full Function Valve - Single valve system - easy to install, maintain and troubleshoot. - Built-in pressure protection and anti-compounding functions. - Space age engineering grade composites: resists corrosion, lighter and more durable than aluminum. - Built-in service and spring brake quick release. - Heavy wall mounting nipple is treated to resist corrosion and withstand severe duty applications. - Service brake priority ensures air tank pressure is sufficient to stop vehicle when spring brakes are first released. - Can be used with single or twin air tanks.