Underground tapes are used for marking, indicating and alerting workers to buried utility installations. There are two common types of underground tapes used for this purpose: 845 Detectable Underground Tape has an aluminum backing making it detectable by a non-ferrous metal detector. 868 Non-Detectable Tape lacks the aluminum backing of the detectable product but still offers a visual indication of utility work, pipes and cable buried below. Both products offer a degree of protection against costly service interruptions and repairs.