Code of thread: fine-pitch thread – FG, left-handed thread-LH, fine-pitch and left-handed thread-FGLH.
Material and surface treatments:
Fork: low carbon steel Q235A; Coated with rust-proof oil, zinc plating or nickel plating.
Shaft: medium carbon steel 45; Coated with rust-proof oil, zinc plating or nickel plating.
Ring: spring steel; Coated with rust-proof oil, zinc plating or nickel plating.