black polypropylene hole cap, thread for 10-425, PTFE/silicone, septum thickness 1.5 mm, for use with 2 mL vial (large opening), pkg of 100 ea. Pricing. 27018. black polypropylene hole cap, thread for 13-425, PTFE/silicone, septum thickness 1.5 mm, for use with 4 mL vial, pkg of 100 ea.