In February 1998, Energy Spectrum formed Spectrum Rotary Compression (“SRC”) to own and operate a fleet of rotary compressor packages for long-term rental and sale to natural gas producers and gatherers. Rotary compressors (also referred to as “screw” compressors) offer operational advantages over traditional reciprocating compressors in low-pressure applications. In April 2000, SRC was merged into Universal Compression Holdings, Inc., which subsequently completed an initial public offering. Energy Spectrum subsequently sold its Universal shares. In 2007, Universal Compression merged with Hanover Compressor Company to form Exterran Corporation.