The Model QRNG325 natural gas compressor is an aircooled, two stage, two cylinder, pressure lubricated compressor, capable of handling inlet pressures of -7.5 PSI (15 in. mercury) up to 30 PSI Up to 500 PSI of discharge pressure can be produced (with proper controls & modifications). It has a 4.5" bore x 2.5" stroke and can be run at 400-900 RPM.