Model Series ring material ---
Category axis cards, hole cards, and other openings ring diameter 6 - 190 (mm)
OD 10 - 210 (mm) thickness of 1-3 (mm)
Surface treatment: black, color, galvanized, etc.
Packaging: carton or in bulk sacks

Heat treatment are: quenched and tempered carbon permeability, vacuum heat treatment, tempering, normalizing.