Features: 【Vial caps material】: 9mm Blue Polypropylene Screw-Thread caps【9mm liner】:9mm red PTFE/white silicone with precision-fit septa provide an evaporation-proof seal.【Vial caps Dimension】: hplc caps diameter 9mm, height 6.2mm.Pack of 100【Easy to use】:9mm Bi-layer includes silicone and PTFE.