These antibiotic sensitivity discs are supplied in cartridges of 50. To transfer to the agar plate simply use a sterile pair of forceps.The cartridges have a long shelf life when correctly stored in a refrigerator.Antibiotic: Penicillin GConcentration: 1.5 unitsPack of 50 discsPlease Note: Nutrient Agar Plates and ejector are not included.