Product Category Information:The stainless steel cylindrical closures are excellent for microbiology and related applications. Non-contaminating closures may be autoclaved repeatedly without loss of resilience. The indentations on the top surface permit adequate exchange of gasses under aerobic and anaerobic conditions, yet prevent dust and micro-organisms from collecting at the top. These noncorrosive closures reduce the amount of specimen evaporation to about half of that of cotton plugging. These closures are available with or without three resilient fingers which permit adjustment to nominal variations in the O.D.