This is a 18mm CRC and TE closure Pipette. The closure has 2 features, one feature is the tamper evident. The ring below the closure part will fall off when you try to open it. Anther feature is that only adult can open the bottle, you will need to push the cap and then rotate the cap. We also can help you customize the glass dip tube length, even customize the cap and bulb color. We can provide mark and logo print service on the glass dip tube too.