Wheaton serum vials are made from Wheaton 320 low-extractable clear borosilicate glass which conforms to USP Type I and ASTM E 438 Type I, Class A requirements. The blow-back feature in the neck and specially designed bottom radius, for added strength are important for lyophilization applications. Tubular design provides excellent clarity and dimensional consistency room vial to vial. Vials are packaged in shrink- wrapped modules to greatly reduce particulate contamination. Autoclavable. 2mL Capacity. 32 H x 15mm Diameter. 7 I.D. x 13mm O.D. Mouth. Clear. Type I Borosilicate Glass. 13mm Cap Size. Wheaton #: 223683.