These colorful snap-on closures are an effective way to recap blood drawing tubes, glass test tubes and plastic culture tubes. They are precision molded from low-density polyethylene (LDPE) and maintain a tight seal during centrifugation, agitation and refrigeration procedures. They are available in bright attractive colors for sample identification purposes.The caps feature one thumb tab for easy removal of the cap. This feature also allows more tubes to be stacked closely in racks than our line of double thumb tab caps.