The Quick Exhaust Piston Housing is designed to rapidly vent the blast of air that is used to advance the loader. By venting the gas quickly, the loader responds instantly. This equates to faster loading with lower pressure.
The standard A5 piston housing has no venting ports (not good). The X7 Piston housing has forward exhaust ports only (better) meaning that it only exhausts the air in front of the piston... not behind it. It's the air behind the piston that's doing all the work, and needs to be vented for faster loading.
TechT's 'QEPH' is a forward AND reverse exhaust tube. It exhausts the air in front of the piston during the piston stroke, and behind the piston at the end of the piston stroke. This means that less pressure is needed to advance the loader, and the loader is allowed to return faster.
TechT was never satisfied with the exhausting capacity of a normal QEV on the cyclone, and after seeing the idea behind the X7 piston housing they took it to the next level, combining those two venting ideas into one part.
The materials used are better than stock piston housings, the internal finish is much smoother with a special coating, and perform much better (increasing speed and efficiency)... And hey, they look way cooler too.
Designed to do what the normal QEV (Quick Exhaust Valve) attempts to do, there are no gaskets to keep clean and exhaust is as fast as physically possible.