The diameter(In/Out) is larger than Tokyo Marui VSR-10.
Made of SUS304(Stainless steel) by CNC machined.
This cylinder has a precise diameter to compress air effectively , so the material is special stainless steel which made by cold hammer ring way.
It's the same as custom inner barrel by 3rd Party made.
We implanted some Pins around the circumference to combine boss block & cylinder body.
And add weld there to reignforce against pulling bolt operation.