*Material:zinc alloy,aluminum alloy,ABS. *Used for oven and gas cooker *Size of the hole:6mm,8mm,8.5mm *OEM service provided specifications:-cookware knobs-material:zinc alloy-size:standard or customized-The size of the hole:6mm,8mm,8.5mm-surface finishes:Nickle plated,chrome plated,or as your request.-various type can be chosen-reliable quality and competitive price!