Microplate well caps are inserted into individual wells to seal the wells, and to protect contents from leakage, contamination, and evaporation during assay processing, incubation, or storage. General use microplate well caps are typically compatible with round 96-well microplates or strips. A subset of microplate well caps are designed for use with a specific application, such as PCR, or a specific plate type. Microplate well caps are plastic, have either flat or domed lids, and are available as individual well caps or as strips of well caps.