aijiren Techbrand™ 10mm PP Screw Seal, Black, Center hole, 10-425 thread, Assembled septum Pre-assembled caps and septa are convenient and minimize contamination from handling. 10 aijiren Techbrand™ 8mm PP Screw Seal, Black, Center hole, 8-425 thread, Assembled septum Polypropylene caps are chemically inert and suitable for most chromatography applications. 11