HP magneto-optical rewritable cartridges allow virtually unlimited read/write cycles, making them the ideal choice for data management in information-intensive environments. HP write-once cartridges are designed for permanent storage of data that can't be altered or erased. Both disk formats have an archival life of 100 years and are engineered to HP's exacting quality standards. Select HP optical disks to enhance the reliability, performance, and longevity of your drive. Each HP optical disk is encased in a sturdy, poly-carbonate casing to inhibit both the attraction of dust particles and static build up.