Aluminium. Anodized in color. Sterilizable. Anodic oxidized. Sterile but non-hermetic closing of vessels. Special caps for culture flasks (without beaded rim) and culture media bottles with straight neck of dia. 38 mm. Springs made of chromium-nickel-steel, with clamp against the outer wall of the vessel.

Advantages: stainless, washable/reusable, heat-resistant, sterilizable, fixed locked, air supply guaranteed, different colors for recognition.