The advanced technology, constant back pressure exhaust brake provides extra engine braking for the HOWO A7 truck. Jacobs uses a special spring to balance the back pressure via moving the seal bar. It can provide higher back pressure at low RPM and control the back pressure at high RPM, so it can provide 20% more power at low RPM than a fixed orifice exhaust brake (FOXB), and protect the engine via release the back pressure when the RPM is too high.