The cut corner of the lid insures only one position for the lid, thus avoiding cross-well contamination. The Orange Scientific logos on the lid and plate being aligned when the lid is positioned correctly, help in this positioning. Each well is further protected by individual rings on the lid. The plates feature handling serration areas on opposite sides. This system insures that one easily notices whether one holds the plate itself or a lid (no serration on the lid), avoiding the lifting of the next lid in a stack by mistake. - Air extraction/ ventilation features allowing maximum external/ internal gas exchange and considerably reduced mediaevaporation without altering the CO₂ diffusion.