External threads result in a smooth inner surface which avoids airborne contamination and sample loss. Screw cap has a moulded sealing ring which givess a leakproof seal without a washer. Caps are blue in colour. CRYO-LOK vials have conical bottoms for maximum sample retrieval and allow centrifugation. A moulded skirt enables vials to stand on a bench.
Knurled sides give a better grip for tightening or removing the cap.
A frosted area for labelling is provided. Working volume graduations are moulded in mL increments up to 2.0mL, 2.5mL and 3.5mL respectively. Although capacity of vials is greater than the top graduation mark, this should not be exceeded when specimens are to be frozen. All vials are 13mm in diameter and fit standard storage cans. Sterilised through gamma irradiation.