The term SRO refers to the fact that the tenant rents a single room, as opposed to a full flat (apartment). While roommates informally sharing an apartment may also have a bedroom and share a bathroom and kitchen, an SRO tenant leases the SRO unit individually. SRO units may be provided in a rooming house, apartment building, or in illegal conversions of private homes into many small SRO rooms. There is a variety of levels of quality, ranging from a "cubicle with a wire mesh ceiling", at the lowest end, to small hotel rooms or small studio apartments without bathrooms, at the higher end. They may also be referred to as "SRO hotels", which acknowledges that many of the buildings are old hotels that are in a poor state of repair and maintenance. The acronym SRO has also been stated to mean "single resident only". The terms "residential hotel" or "efficiency unit" are also used to refer to some SROs.