For all pumps with dry-Pac system fitted. One sachet of dry-Pac medium for complete refill of dry-Pac cartridge. For optimum performance the dry-Pac should be renewed every 4-6 months depending upon usage. The dry-Pac medium is vacuum packed and can be stored indefinitely providing the vacuum remains intact.Now includes our updated Colour Changing Dry-Pac system. The beads in the medium will now gradually change colour from Orange to Green as they absorb moisture to indicate that they need to be changed for a fresh sachet.