Cap materials: Polypropylene, aluminum, tin/steel/nickel coated, bimetal, phenolic. Septa liner and film materials: Silicone, silicone with PTFE, silicone with polyimide, silicone with FEP, butyl, foam, viton. Septa thickness range: 0.25 mm to 4 mm. Septa configurations: Non slit, straight slit, star slit, cross slit, Y-cut, step slit, washer.