Septa only for 8-425 Open Top Screw Caps 8-SP100110000/pk8mm Red PTFE/White Silicone 1mm (.040 in) thick 8-SP100210000/pk8mm Red PTFE/White Silicone 1.3mm (.050 in) thick 8-SP100310000/pk8mm Red PTFE/White Silicone 1.5mm (.060 in) thick, 8-SP100410000/pk8mm Red PTFE/White Silicone 1.5mm (.060 in) thick, PRE-SLIT 8-425 Open Top Screw Caps (Polypropylene) Part No.UnitDescription 8-SP200110000/pkBlack,8-425 Open Top Screw Cap