4ml Thread HPLC Vials. 4ml Screw Neck hplc Vials ND13 with matched 13-425 PP Screw caps, PTFE/silicone septa, widely used in HPLC and GC analysis. Features. Materials:borosilicate glass. Volume:4ml, 15 x 45 mm. Vial Color: Clear & Amber. Septa material:PTFE & silicone septa. Cap:blackcap with 13-425 thread. Cap with closed top or with centre hole.