Classic stainless-steel covers with silicone seals:

• the most robust cover: can be used for many years, with only an occasional need for filter replacement
• relatively heavy: 170-200 g
• meant for manual handling: 
  • surface at sides too slippery for the average robotic gripper (though some groups address this with some autoclave tape put on the sides)
  • tight fit: only ~ 0.5 mm robotic mispositioning allowed
• autoclavable
• needs a high clamping force for a good sealing, and to prevent rattling during orbital shaking
• can not be used as a cover during centrifugation (too heavy; it will destroy the microplate underneath)

Robot-friendly covers with a flat carbon plate, and an SEBS structured seal

• relatively light: 80 - 100 g
• meant for robotic and manual handling:
  • surface at the sides has a good grip (SEBS rubber, with a high friction coefficient)
  • has a thin stainless steel side, under an angle of 5 degrees, so that mispositioning by the robot of 1 mm is allowed
• autoclavable (best: on a flat surface, because the carbon is prone to warping during autoclaving)
• needs a moderate clamping force for a good sealing.
• can not be used as a cover during centrifugation (the stainless steel part will be torn out of the rubber part)

Disposable covers, made from medical grade polystyrene, and with a PEVA seal

• very light (~ 23 g)
• meant for robotic and manual handling:
  • surface at the side has a good grip; structured)
  • sides flare out (under an angle of 5 degrees), so that mispositioning by the robot of 1 mm is allowed
• supplied gamma-irradiated, on top of the microplate:
  • time-efficient
  • no need to dispose of the regular polystyrene lid that is normally on top of the microplate
• non-autoclavable, so in principle single-use (though some groups re-use the covers several times, after exposure to ethanol vapour and/or UV light)
• needs a moderate clamping force for a good sealing.
• can be left on top of the microplate during centrifugation