The outer cylinder is maintained sufficient hardness by heat treatment, therefore it ensures the bushings projected travel life and satisfactory durability.
The ball retainer is made from steel or resin. The steel retainer has high rigidity obtained by heat treatment, thus have higher using temperature of -40~125℃.
While normal resin retainer have using temperature of -20~80℃。
All models can be done with nickle plated (rust-proof) based on customers' requirements.