Longfei Group --Introduction - Engaged in the development, design, product, sale, installment and service of Medical Health Care Oxygen Concentrator, PSA Oxygen Generator and Medical Oxygen System. - Established at 1997, has 10 years experience on this field.- We take at least 70% market in China. So we are confident about the quality of our products- Have the import and export right in self-support,- Has passed CMDC quality certification, ISO9001 international quality system, CE certification. and some has passed FDA,- Offer one-year charge-free maintenance and lifetime warranty (only charge for the components used).