Opto-mechanical treatment of growth area for optimal cell adhesion. Lid with air-venting system guarantees controlled gas exchange with low evaporation. Sloped edge allows placement of the lid in one position only. Yellow marking area on lid and plate ensure correct lid orientation: yellow on yellow – match! Ridged grip area ensures a secure grasp and prevents from accidentally lifting off the lid. Clear alpha-numerical labelling between the wells for easy orientation during microscopy, easy to see black alpha-numerics on the side. Air vents in plate base prevent condensation and provide consistent air-flow between stacked plates.