These 3ml cartridges are compatible with many pen devices ensuring reliable and precise delivery. Each cartridge is sterilized by ultraviolet light technology, then individually sealed. Twenty of these cartridges were randomly selected and sent to an independent test lab to verify sterilization. Test lab results can be found in the pictures for this listing. These are manufactured with medical-grade borosilicate glass. These aree ideal for users who require regular replacement of injection device components to maintain compliance. This offerng is for a 20 pack of cartridges.