What are the different cap closures?

The flexible sealing lip inside the cap ensures a positive leakproof seal under the most adverse conditions. The deep internal lip is made to fit securely against the interior wall of the tube preventing the contents from coming into contact with the threads, thus reducing the chances of sample contamination. By nature, the lip seal functions by maintaining a constant friction between the lip and the tube. 

The O-ring is a red circular, ring-shaped piece that sits in the groove between two parts; the lid and the tube. The compression of the two parts creates the airtight and liquid-tight seal.

The specially designed silicone washer found in the cap ensures a positive leakproof seal at all temperatures. Once the cap is screwed onto the tube, the silicone washer is tightly secured between the cap and the top of the tube, guaranteeing a secure seal.

The tamper evident cap incorporate a ring that needs to be broken in order to remove it, leaving an obvious visual indication that the vial has been opened.