* Made in the USA * The simplified  two-piece cabinet design allows for 15% typical sound quality improvement and an improved cooling process * DeVilbiss Turn-Down Technology minimize wear on internal components and increase the life expectancy of the unit * The concentrator is easy to assemble and disassemble * Assorted replacement filters for the Devilbiss 505  515 and 525 Oxygen Concentrators * The 5xx series concentrators use 3 filter types: AIR FILTER 6/PKG (505DZ-604)  INTAKE FILTER SILENCER ( 515DZ-605)  and FINAL BACTERIA FILTER (PV5LD-651)