This tightbore 6.01mm diameter inner barrel fits the Tokyo Marui Detonics .45 gas blow back pistol. The extremely tight diameter requires premium ammunition as anything less can result in jamming, loss of power and/or accuracy and even damage to the barrel.
What is Palsonite you ask?
Palsonite is to stainless steel, as anodizing is to aluminum. It is an incredibly hard surface treatment, it makes the steel surface more resistant against corrosion and wear, and reduces friction. Palsonite affects the metal itself, so it is not a coating that could chip off but actually the very surface of the material that is changed into Palsonite.
It has a distinct black color to it, a side-effect of the treatment which happens to make very cool looking inner barrels for Airsoft pistols. This is particularly true with Airsoft as their dark tone makes them disappear inside the shadow of the outer barrel in most cases so the outer barrel appears to be the only barrel which adds to realism. Even when barrel and slide compensators are used, the holes expose a barely visible black inner barrel instead of a bold brassy or silvery colored rod which again adds to realism.