ZCI Full Cylinder Aluminum (Type 0)

This Cylinder has a very nice finish inside and is ideal for the free flowing of a piston. I'm not sure if there's a way to prove this but I would venture to say that it possibly could improve ROF slightly due to the piston's easier movement with minimal friction.

Only reason it doesn't deserve 5 stars is because it's aluminum, which is much more prone to bending. So if you're not careful with it (for example if you clamp it down like I did with my stock brass cylinder to work on it, which was the reason I bought this one), it could be slightly crushed and the piston will have incredible resistance when passing the crushed part of the cylinder.

Overall, good product. Does it's job good.