Model: T200-2 External Diameter: approx 51mm Inside Diameter: approx 32mm Thickness: approx 14mm Model:T157-2 External Diameter: approx 40mm Inside Diameter: approx 24mm Thickness: approx 14 Inductance coefficient :AL 14nH/N2 Permeability: 10μo approx Material: Iron Color: Red Grey QTY:1PCS The core itself isn't always magnetic