The Citation Jet CJ1 + was developed by the American Cessna Aircraft Company. The design is similar to the CJ1 with a number of innovations. The Collins Pro Line 21 aviation system is present, including two adaptive flight displays, an HSI liquid crystal display, as well as an ADJ display for the co-pilot and other important modern equipment. The CJ1 + is an upgraded version of the CJ1 aircraft. Powered by twin Williams FJ44-1AP engines, the CJ1 + has a maximum take-off weight of 45 kg over the original CJ1.