VWR® Petri Dishes are manufactured from high-clarity polystyrene (PS) and are designed for microbiological culture, cell biology, and environmental monitoring applications. Standard 90 mm diameter dishes comply with ISO 7218 microbiological standard requirements. Key features include: interlocking lid and base for secure stacking, vented design for gas exchange, smooth internal surface for even agar distribution, and grid-marked base for easy colony counting. Available as non-sterile (for media preparation) and gamma-irradiated sterile variants. Also available as contact plates pre-filled with TSA or SDA culture media for surface environmental monitoring. Suitable for use with all standard colony counters and image analysis systems. Packed in sleeves of 20.