These antibiotic sensitivity discs are supplied in cartridges of 50 discs. To transfer the discs to the agar plate simply use a sterile pair of forceps. The cartridges have a long shelf life when correctly stored in a refrigerator at 4°C.Antibiotic: StreptomycinConcentration: 25µgPack of 250 discs (5 x packs of 50 discs)Please Note: Nutrient Agar Plates and ejector are not included.