Sectional Contoured Matrix Bands M4: 3.5mm, 4.5mm, 5.5mm, 6.5mm. ●Matrix Bands M4 2.0 50/100Pcs Matrix Bands M4 2.0. The inner surface is coated with a special non-stick ultra-thin coating, which greatly reduces the viscosity of the composite resin and adhesive with the forming sheet, making the forming sheet easier to separate and remove.