CYMA produced nylon-fiber full-steel rack piston. Very popular at the moment, regarded as one of the strongest metal injection molded pistons. These have CYMA's have blackened heat-treated steel racks and a new blue hex shaped body.
It's 15 teeth so if you need to correct the AOE you'll need to shave dow the 2nd / 3rd tooth. The rack isn't locked down.
Tested at 6000 cycles, see video for more information.
Teeth rail width: 6mm
Piston body width (guide rail to guide rail): 21.5mm
Weight = 16g
Length = 66.6mm