These antibiotic sensitivity discs are packed in cartridges of 50. To transfer onto the the agar plate simply use a sterile set of forceps. The cartridges have a long shelf life when correctly stored in a refrigerator at 4°C.Antibiotic: Penicillin GConcentration: 1.5 unitsPack of 250 discs (5 x cartridges of 50 discs)Please Note: Nutrient Agar Plates and ejector are not included.