The SDLT is an evolution of DLT tapes originally developed by Quantum.
The management of the reading heads is done by a laser beam (LGMR). Both sides of the tape are used. One for storing data, and the other for storing tracking and positioning information. This second side that is used by the laser beam.
Thanks to the use of lasers, the accuracy of head positioning is increased, as the storage capacity.
The DLT and SDLT cartridges are the same size, measuring 105.7 mm wide x 105.4 mm long x 25.4 mm high. Tape lengths vary from 557 to 630 meters, tape width is the same for both, 12.7 mm.