A single reel data tape cartridge (10) housing includes a base (38) and a cover (40). The base (38) includes four outer side walls (42) which are formed with at least one step such that the outer walls step to a decreased thickness toward their free end. The cover (40) includes four outer side walls (54) which are formed with at least one step such that the outer walls step to a decreased thickness toward their free end. The base (38) and cover (40) also include four inner walls (68, 78) which are formed with two steps such that the inner walls step to a decreased thickness toward their free end. The inner and outer walls (78, 54) of the cover (40) complementarily mate with the inner and outer walls (68, 42) of the base (38). A projection (112) can be placed within pockets (114) in the base (38) and cover (40) to locate the base and cover during assembly.
