We did nickel coating for the best performance. This material makes stable layer and erase minor defects. Layer thickness is around 20 µm. Here are basic characteristics of the nickel surface: High anti rust protection stable uniform coating layer Atractive look (half shiny or shiny) Roughness Good sliding characteristics Cylinder is suitable for rifles Marui VSR and copies made ​​by Well (MB-02, 03, 07, 10, 11, 12 ..). The inner diameter of the cylinder is smallerdue to nickel coating so cylinder can be only be combined with a 90 ° set, for VSR rifles! The original pistons may jam inside and we can not  ensure proper operation.