We do not recommend to perform readouts with a cover on the microplate, as this typically increased errors/variability. Plate sealer films may be used, but we recommend to monitor readout value variation and control for condensation or drops forming on the film. We are not aware of a plate/lid combination with a hard plastic lid, which would fit into the slot of the plate reader. The plate reader is compatible with all 96-well plates adhering to ANSI/SLAS standards for microplates (https://www.slas.org/education/ansi-slas-microplate-standards/).