The DLTVS1-CL is a cleaning cartridge by Sony for use with DLT-VS tape drives and auto-libraries. According to the Sony site these DLTVS1-CL cleaning cartridges can last for up to 20 cleaning cycles. The DLTVS1-CL is a cleaning tape and like all cleaning cartridges it should only be used when the cleaning lamp or light or LED on your tape drive lights up. This is because using a cleaning tape such as the DLTVS1-CL ensures that your tape drive remains at top notch however, excessive use causes wear on the read/write heads and will cause the running life of your tape drive to decrease significantly. Another method for using cleaning tapes such as the DLTVS1-CL is to set up a routine, like once in a fortnight or once every 3 full backups etc.