Foam Plug, fits 14-20mm Openings, Assorted Colors. Identi-Plugs are for use with test tubes and flasks. They are reusable and leave no clinging fibers like cotton plugs. They provide a snug fit, yet permit free air flow. Plugs are ideal for use with Drosophila vials. They spring back to original shape after repeated use. Identi-Plugs can also be used as a cleaner for lab pipettes, tubes, vials, as well as industrial precision tubing. All plugs are approximately 1.75" long, except CGE-1490-066, which is approximately 3.5" long. The Assorted Color Variety Pack includes four plugs each of charcoal grey, blue, and white.