Dishes meet or exceed the standards for equipment and materials listed by the United States Safe Drinking Water Act and as approved by the EPA and referenced in "The standard methods for water and waste water." Precision design and manufacturing assures a tight-fitting lid that prevents dehydration of pads or nutrients without affecting organism growth. Dishes are free of growth-inhibiting substances that could directly or indirectly interfere with bacterial growth. Compliance with good manufacturing practices assures a pyrogen-free product. Twenty dishes are packed in each contaminant-free polyethylene sleeve providing cleanliness and sterility.