A combined piston/head/sector gear set from G&P, this package is a good choice for people looking to rock more intense gearbox setups. The piston itself is 7075 Aluminum for strength and low weight whilst sporting piston teeth and a sector gear of MRC 38-40 Steel. The piston head is a more normal plastic however, keeping wear down throughout cycling.
This is a series of four with the differing factor being the piston teeth count; model D is standard full teeth, model C has one less tooth on the front, B one less again and A yet one more less. The purpose of the saved teeth, for those not in the know, is to adjust the sector gear-piston engagement timing as higher speed weapons are know to turn over so fast that piston timing can crunch teeth.
Now, rather then having to perform fiddly work yourself to shave teeth, you can buy this middleweight, high strength piston set and simply select what teeth count you need.