Shanghai Jingoo Petroleum Apparatus Co., Ltd. is the first specialized supplier of API gauges and professional calibration services in China. We have been in business for over 18 years and have served over 1000 customers in 36 countries. We are certified material supplier for the following companies: Schlumberger, China National Petroleum Corporation, GE Oil & Gas, ITS UAE & UK, Smith International, Besmindo, Weatherford, Hilong Group, etc.All our gauges come with third-party calibration certificates that are traceable to NIST and valid for API audit. We make sure every set of gauges we send out to you strictly conforms to API specifications.