The diammeter(In/Out) is same as Tokyo Marui VSR-10.
Made of SUS304(Stainless steel) by CNC machined.
We processed "PALSONITE" surface treatment to reignforce the durability to stainlesss steel.
And be black surface as real.
This cylinder has a precise diameter to compress air effectively , so the material is special stainless steel which made by cold hammerring way.
It's the same as custom inner barrel by 3rd Party made.
The tolerance described by our company refers to the "straight" part which is not machined.
The slotted part is not related to the airtight performance so its tolerance is not design to be as tight as other places.
About Inner Dia. actually a little bit smaller so if using an original piston,or 3rd party upgrades,you feel a little hard.
We recommend using PDI upgrades for Precision Cylinder.
We implanted some Pins around the circumference to combine boss block & cylinder body.
And add weld there to reignforce against pulling bolt operation.