The Pratt & Whitney APS2300 APU was designed for the rigorous utilization of 60- to 110-passenger regional jet aircraft, namely the Embraer 170/195-series aircraft. The APS2300 is generally accepted as the industry’s most reliable APU available today. The APS2300 APU is installed in Embraer's fleet of E170/175/190/195 regional jets as well as Embraer's Lineage 1000 business jets. The APS2300 APU is an integral bleed, constant speed, continuous cycle gas turbine engine that incorporates a single-stage centrifugal compressor, a reverse flow annular combustor, and a two-stage axial turbine. The APS2600 APU is the latest generation regional aircraft APU system available today. Derived from the APS2300, it has been designed to match today's regional market requirements.