The object is part of the IBM 7950 Harvest system. It is a cartridge for the TRACTOR tape system, which is described in a Wikipedia entry as follows, "The TRACTOR tape system, part of the HARVEST system, was unique for its time. It included six tape drives, which handled 1.75-inch-wide (44 mm) tape in cartridges, along with a library mechanism that could fetch a cartridge from a library, mount it on a drive, and return it to the library. The transfer rates and library mechanism were balanced in performance such that the system could read two streams of data from tape, and write a third, for the entire capacity of the library, without any time wasted for tape handling."
