E&C 15 full bodied polymer piston together with a 15 tooth full steel rack. The thickness of the piston material is around 3mm, most brands (SHS, CYMA etc) are around 2mm. The piston has a large rack contact area making it better to glue down. As with all pistons I recommend you fixing down the rack with a strong glue / epoxy. Inner diameter of Piston is 15mm.
The Piston Head is made from aluminium, gives a very good seal, has 8 vents and comes with bearing.