... Features:Phenolic/Bakelite Waviness Lobe Handle Knob With leadscrew/inner thread 1.Material:Plastic, bakelite, zinc alloy, phenolic, polyamide2.Surface treatment ... , sand blasting, grinding and etc.3.Leadscrew material: stainless steel, iron, high strenghth steel4.leadscrew treatment: zinc plated, nickel plated, chromated ...