Sony DLT IV 40GB/80GB Data Tape Cartridge DL4TK88. A single DLTTapeIV cartridge has a native capacity of 35MB (up to 70MB compressed) and a data transfer rate of 5MB/s(up to 10MB/s compressed) using the top-end DLT7000 drive. Adaptive cache buffering multiple heads longitudinal serpentine tracks and high tape speed contribute to this outstanding performance.